# Electronic Supplementary Material (ESI) for ChemComm.
# This journal is © The Royal Society of Chemistry 2020

####################################################################### 
# 
# This file contains crystal structure data downloaded from the 
# Cambridge Structural Database (CSD) hosted by the Cambridge 
# Crystallographic Data Centre (CCDC).
# 
# Full information about CCDC data access policies and citation 
# guidelines are available at http://www.ccdc.cam.ac.uk/access/V1 
# 
# Audit and citation data items may have been added by the CCDC. 
# Please retain this information to preserve the provenance of 
# this file and to allow appropriate attribution of the data. 
# 
#######################################################################

data_Alloxan_0p57GPa
_database_code_depnum_ccdc_archive 'CCDC 1994628'
loop_
_audit_author_name
_audit_author_address
'Nicholas Funnell'
;STFC, ISIS Neutron Facility
United Kingdom
;
_audit_update_record             
;
2020-04-03 deposited with the CCDC.	2020-05-01 downloaded from the CCDC.
;
# start Validation Reply Form
_vrf_PLAT699_Alloxan_0p57GPa     
;
PROBLEM: Missing _exptl_crystal_description Value .......     Please Do !
RESPONSE: Not applicable - powder sample.
;
_vrf_PLAT430_Alloxan_0p57GPa     
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.84 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT041_Alloxan_0p57GPa     
;
PROBLEM: Calc. and Reported SumFormula    Strings  Differ     Please Check
RESPONSE: This is possibly an erroneous alert? The calculated and reported formulae appear to be the same.
;
_vrf_PLAT340_Alloxan_0p57GPa     
;
PROBLEM: Low Bond Precision on  C-C Bonds ...............      0.008 Ang.
RESPONSE: The structure is refined against high-pressure data which suffer from higher signal-to-noise and lower peak resolution that standard powder patterns. Direct refinement of the atomic coordinates is not possible and so the molecular geometry is constrained via a rigid body. This has all led to the low bond precision seen here.
;

_chemical_name_systematic        pyrimidine-2,4,5,6-tetraone
_chemical_name_common            alloxan
_chemical_formula_moiety         'C4 O4 N2 H1.50 D0.50'
_chemical_formula_structural     'C4 O4 N2 H1.50 D0.50'
_chemical_formula_sum            'C4 O4 N2 H1.50 D0.50'
_chemical_formula_weight         142.58
_chemical_compound_source        Sigma-Aldrich

_space_group_crystal_system      Tetragonal
_symmetry_space_group_name_Hall  'P 4abw 2nw'
_space_group_name_H-M            P41212
_symmetry_Int_Tables_number      92

loop_
_symmetry_equiv_pos_as_xyz
'x, y, z '
'-x+1/2, y+1/2, -z+1/4 '
'-y, -x, -z+1/2 '
'-y+1/2, x+1/2, z+1/4 '
'y, x, -z '
'y+1/2, -x+1/2, z-1/4 '
'-x, -y, z+1/2 '
'x+1/2, -y+1/2, -z-1/4 '

_cell_length_a                   5.8059(8)
_cell_length_b                   5.8059(8)
_cell_length_c                   13.905(2)
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_volume                     468.73(15)
_cell_formula_units_Z            4

_cell_measurement_temperature    293.00000
_cell_measurement_pressure       0.57418 #GPa

_cell_special_details            
;
Cell parameters included in refinement
;

_exptl_crystal_density_diffrn    2.020

_pd_spec_mounting                'TiZr Capsule'
_pd_spec_mount_mode              transmission
_pd_char_colour                  yellow
_chemical_absolute_configuration .

_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details   
;
Calculated using MANTID routines.
;

_pd_instr_location               
'ISIS Neutron Facility. Rutherford Appleton Laboratory'
_diffrn_ambient_temperature      293.00000
_diffrn_source                   'Pulsed neutron source'
_diffrn_source_target            W
_diffrn_radiation_type           Neutron
_diffrn_measurement_device_type  'PEARL diffractometer'
_diffrn_radiation_monochromator  none
_diffrn_detector                 'ZnS scintillator'
_diffrn_detector_type            custom

_pd_meas_scan_method             Time-of-flight
_pd_meas_special_details         
;
Time of flight method using a pulsed neutron source
;

# The following three items are used for time-of-flight measurements only.
_pd_instr_dist_src/spec          12800
_pd_instr_dist_spec/detc         800
_pd_meas_2theta_fixed            90

_pr_proc_ls_profile_function     
;
Voigt function convoluted with a back-to-back double exponential.
;

_pd_proc_ls_background_function  'Chebychev polynomial'

_pd_proc_ls_pref_orient_corr     
;
No requirement for preferred orientation correction
;

_refine_ls_goodness_of_fit_all   0.76512
_pd_proc_ls_prof_R_factor        3.30972
_pd_proc_ls_prof_wR_factor       3.24425
_pd_proc_ls_prof_wR_expected     4.24019
_refine_ls_R_I_factor            2.05180
_refine_ls_matrix_type           sparse
_refine_ls_weighting_scheme      sigma
_refine_ls_weighting_details     ?
_refine_ls_hydrogen_treatment    ?
_refine_ls_extinction_method     none
_refine_ls_number_parameters     42
_refine_ls_number_restraints     ?
_refine_ls_number_constraints    ?
_refine_diff_density_max         ?
_refine_diff_density_min         ?
_refine_ls_shift/su_max          <0.01


_pd_proc_info_data_reduction     
;
Data reduction performed using Mantid
;

_refine_special_details          
;
The molecular structure is refined via a rigid body Z-matrix. All 
intramolecular geometry is constrained to the values determined from 
high-resolution powder neutron data (ALOXAN14). These parameters are not
expected to change with pressure.

Refinements show that the sample is only partially deuterated. H and D atoms 
sites were both included in the refinement, where an overall H/D occupancy is 
refined against all data.

Isotropic displacement parameters for C and N atoms are allowed to refine for 
lower-pressure structures. Parameters for the O and D/H atoms were fixed at 
1.5x the value of the parent atoms, due to unstable refinement - these ratios 
are informed by the approximate values obtained when refining against a 
preliminary data collection carried out in a vanadium can (not reported). Above
approximately 3 GPa, no displacement parameters could be stably refined, so 
they were then held fixed to the last stably-refined values.

The number of parameters quoted in the CIFs for each pressure point, includes 9
background terms and 23 parameters corresponding to contaminant phases (WC, Ni 
and Pb) which arise from the sample environment. Alloxan accounts for 10 of the
number of parameters quoted.

Sample pressures are determined using the refined lead lattice parameter and a 
Birch-Murnaghan equation of state.
;


#CHECK-CIF ALERTS


loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_symmetry_multiplicity
_atom_site_adp_type
_atom_site_B_iso_or_equiv
H1 H 0.1600(14) -0.2280(14) -0.1031(6) 0.748(6) 8 Biso 0.4(3)
D1 D 0.1587(14) -0.2139(14) -0.0990(6) 0.252(6) 8 Biso 0.4(3)
N1 N 0.1461(12) -0.0680(12) -0.0569(3) 1 8 Biso 0.28(18)
C1 C -0.0482(11) -0.0482(11) 0.000 1 4 Biso 0.61(14)
C2 C 0.3227(12) 0.0863(12) -0.0628(4) 1 8 Biso 0.61(14)
C3 C 0.2994(11) 0.2994(11) 0.000 1 4 Biso 0.61(14)
O1 O -0.1975(11) -0.1975(11) 0.000 1 4 Biso 0.9(2)
O2 O 0.4881(15) 0.0555(15) -0.1149(6) 1 8 Biso 0.9(2)
O3 O 0.4448(11) 0.4448(11) 0.000 1 4 Biso 0.9(2)


loop_
_geom_bond_atom_site_label_1
_geom_bond_atom_site_label_2
_geom_bond_distance
_geom_bond_site_symmetry_1
_geom_bond_site_symmetry_2
_geom_bond_publ_flag
O(1) C(1) 1.226(9) . . no
O(2) C(2) 1.216(11) . . no
O(3) C(3) 1.194(9) . . no
N(1) C(1) 1.383(8) . . no
N(1) C(2) 1.364(10) . . no
C(2) C(3) 1.520(8) . . no
N(1) H(1) 1.132(10) . . no
N(1) D(1) 1.032(10) . . no

loop_
_geom_angle_atom_site_label_1
_geom_angle_atom_site_label_2
_geom_angle_atom_site_label_3
_geom_angle
_geom_angle_site_symmetry_1
_geom_angle_site_symmetry_2
_geom_angle_site_symmetry_3
_geom_angle_publ_flag
C(1) N(1) C(2) 126.4(6) . . . no
O(1) C(1) N(1) 121.2(5) . . . no
O(1) C(1) N(1) 121.2(5) . . . no
N(1) C(1) N(1) 117.6(6) . . . no
O(2) C(2) N(1) 122.2(7) . . . no
O(2) C(2) C(3) 122.1(7) . . . no
N(1) C(2) C(3) 115.7(6) . . . no
O(3) C(3) C(2) 120.8(5) . . . no
O(3) C(3) C(2) 120.8(5) . . . no
C(2) C(3) C(2) 118.3(6) . . . no
C(1) N(1) H(1) 116.8(7) . . . no
C(1) N(1) D(1) 116.8(8) . . . no
C(2) N(1) H(1) 116.8(7) . . . no
C(2) N(1) D(1) 116.8(7) . . . no


loop_
_geom_torsion_atom_site_label_1
_geom_torsion_atom_site_label_2
_geom_torsion_atom_site_label_3
_geom_torsion_atom_site_label_4
_geom_torsion
_geom_torsion_site_symmetry_1
_geom_torsion_site_symmetry_2
_geom_torsion_site_symmetry_3
_geom_torsion_site_symmetry_4
_geom_torsion_publ_flag
C(2) N(1) C(1) O(1) 180.0(6) . . . . no
C(2) N(1) C(1) N(1) 0.0(8) . . . . no
C(1) N(1) C(2) O(2) 180.0(7) . . . . no
C(1) N(1) C(2) C(3) 0.0(9) . . . . no
O(2) C(2) C(3) O(3) 0.0(9) . . . . no
O(2) C(2) C(3) C(2) 180.0(7) . . . . no
N(1) C(2) C(3) O(3) 180.0(5) . . . . no
N(1) C(2) C(3) C(2) 0.0(7) . . . . no
H(1) N(1) C(1) O(1) 0.0(9) . . . . no
H(1) N(1) C(1) N(1) 180.0(7) . . . . no
H(1) N(1) C(2) O(2) 0.0(11) . . . . no
H(1) N(1) C(2) C(3) 180.0(6) . . . . no
_exptl_crystal_colour            yellow
_symmetry_space_group_name_H-M   P41212
####################################################################### 
# 
# This file contains crystal structure data downloaded from the 
# Cambridge Structural Database (CSD) hosted by the Cambridge 
# Crystallographic Data Centre (CCDC).
# 
# Full information about CCDC data access policies and citation 
# guidelines are available at http://www.ccdc.cam.ac.uk/access/V1 
# 
# Audit and citation data items may have been added by the CCDC. 
# Please retain this information to preserve the provenance of 
# this file and to allow appropriate attribution of the data. 
# 
#######################################################################

data_Alloxan_3p08GPa
_database_code_depnum_ccdc_archive 'CCDC 1994633'
loop_
_audit_author_name
_audit_author_address
'Nicholas Funnell'
;STFC, ISIS Neutron Facility
United Kingdom
;
_audit_update_record             
;
2020-04-03 deposited with the CCDC.	2020-05-01 downloaded from the CCDC.
;
# start Validation Reply Form
_vrf_PLAT699_Alloxan_3p08GPa     
;
PROBLEM: Missing _exptl_crystal_description Value .......     Please Do !
RESPONSE: Not applicable - powder sample.
;
_vrf_PLAT430_Alloxan_3p08GPa     
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.68 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT430_Alloxan_3p08GPa_2   
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.68 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT430_Alloxan_3p08GPa_3   
;
PROBLEM: Short Inter D...A Contact  O1       ..O3       .       2.71 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT041_Alloxan_3p08GPa     
;
PROBLEM: Calc. and Reported SumFormula    Strings  Differ     Please Check
RESPONSE: This is possibly an erroneous alert? The calculated and reported formulae appear to be the same.
;
_vrf_PLAT340_Alloxan_3p08GPa     
;
PROBLEM: Low Bond Precision on  C-C Bonds ...............      0.007 Ang.
RESPONSE: The structure is refined against high-pressure data which suffer from higher signal-to-noise and lower peak resolution that standard powder patterns. Direct refinement of the atomic coordinates is not possible and so the molecular geometry is constrained via a rigid body. This has all led to the low bond precision seen here.
;
_vrf_PLAT430_Alloxan_3p08GPa_4   
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.90 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT430_Alloxan_3p08GPa_5   
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.90 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;

_chemical_name_systematic        pyrimidine-2,4,5,6-tetraone
_chemical_name_common            alloxan
_chemical_formula_moiety         'C4 O4 N2 H1.50 D0.50'
_chemical_formula_structural     'C4 O4 N2 H1.50 D0.50'
_chemical_formula_sum            'C4 O4 N2 H1.50 D0.50'
_chemical_formula_weight         142.58
_chemical_compound_source        Sigma-Aldrich

_space_group_crystal_system      Tetragonal
_symmetry_space_group_name_Hall  'P 4abw 2nw'
_space_group_name_H-M            P41212
_symmetry_Int_Tables_number      92

loop_
_symmetry_equiv_pos_as_xyz
'x, y, z '
'-x+1/2, y+1/2, -z+1/4 '
'-y, -x, -z+1/2 '
'-y+1/2, x+1/2, z+1/4 '
'y, x, -z '
'y+1/2, -x+1/2, z-1/4 '
'-x, -y, z+1/2 '
'x+1/2, -y+1/2, -z-1/4 '

_cell_length_a                   5.6443(8)
_cell_length_b                   5.6443(8)
_cell_length_c                   13.507(2)
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_volume                     430.30(14)
_cell_formula_units_Z            4

_cell_measurement_temperature    293.00000
_cell_measurement_pressure       3.07546 #GPa

_cell_special_details            
;
Cell parameters included in refinement
;

_exptl_crystal_density_diffrn    2.201

_pd_spec_mounting                'TiZr Capsule'
_pd_spec_mount_mode              transmission
_pd_char_colour                  yellow
_chemical_absolute_configuration .

_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details   
;
Calculated using MANTID routines.
;

_pd_instr_location               
'ISIS Neutron Facility. Rutherford Appleton Laboratory'
_diffrn_ambient_temperature      293.00000
_diffrn_source                   'Pulsed neutron source'
_diffrn_source_target            W
_diffrn_radiation_type           Neutron
_diffrn_measurement_device_type  'PEARL diffractometer'
_diffrn_radiation_monochromator  none
_diffrn_detector                 'ZnS scintillator'
_diffrn_detector_type            custom

_pd_meas_scan_method             Time-of-flight
_pd_meas_special_details         
;
Time of flight method using a pulsed neutron source
;

# The following three items are used for time-of-flight measurements only.
_pd_instr_dist_src/spec          12800
_pd_instr_dist_spec/detc         800
_pd_meas_2theta_fixed            90

_pr_proc_ls_profile_function     
;
Voigt function convoluted with a back-to-back double exponential.
;

_pd_proc_ls_background_function  'Chebychev polynomial'

_pd_proc_ls_pref_orient_corr     
;
No requirement for preferred orientation correction
;

_refine_ls_goodness_of_fit_all   0.91599
_pd_proc_ls_prof_R_factor        2.62522
_pd_proc_ls_prof_wR_factor       2.59944
_pd_proc_ls_prof_wR_expected     2.83783
_refine_ls_R_I_factor            1.69348
_refine_ls_matrix_type           sparse
_refine_ls_weighting_scheme      sigma
_refine_ls_weighting_details     ?
_refine_ls_hydrogen_treatment    ?
_refine_ls_extinction_method     none
_refine_ls_number_parameters     40
_refine_ls_number_restraints     ?
_refine_ls_number_constraints    ?
_refine_diff_density_max         ?
_refine_diff_density_min         ?
_refine_ls_shift/su_max          <0.01


_pd_proc_info_data_reduction     
;
Data reduction performed using Mantid
;

_refine_special_details          
;
The molecular structure is refined via a rigid body Z-matrix. All 
intramolecular geometry is constrained to the values determined from 
high-resolution powder neutron data (ALOXAN14). These parameters are not
expected to change with pressure.

Refinements show that the sample is only partially deuterated. H and D atoms 
sites were both included in the refinement, where an overall H/D occupancy is 
refined against all data.

Isotropic displacement parameters for C and N atoms are allowed to refine for 
lower-pressure structures. Parameters for the O and D/H atoms were fixed at 
1.5x the value of the parent atoms, due to unstable refinement - these ratios 
are informed by the approximate values obtained when refining against a 
preliminary data collection carried out in a vanadium can (not reported). Above
approximately 3 GPa, no displacement parameters could be stably refined, so 
they were then held fixed to the last stably-refined values.

The number of parameters quoted in the CIFs for each pressure point, includes 9
background terms and 23 parameters corresponding to contaminant phases (WC, Ni 
and Pb) which arise from the sample environment. Alloxan accounts for 8 of the
number of parameters quoted.

Sample pressures are determined using the refined lead lattice parameter and a 
Birch-Murnaghan equation of state.
;


#CHECK-CIF ALERTS


loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_symmetry_multiplicity
_atom_site_adp_type
_atom_site_B_iso_or_equiv
H1 H 0.1637(11) -0.2431(11) -0.1036(4) 0.748(6) 8 Biso 0.36426
D1 D 0.1623(11) -0.2284(11) -0.0995(4) 0.252(6) 8 Biso 0.36426
N1 N 0.1477(10) -0.0768(10) -0.0572(2) 1 8 Biso 0.24284
C1 C -0.0543(9) -0.0543(9) 0.000 1 4 Biso 0.32639
C2 C 0.3296(10) 0.0818(10) -0.0631(3) 1 8 Biso 0.32639
C3 C 0.3033(9) 0.3033(9) 0.000 1 4 Biso 0.32639
O1 O -0.2079(9) -0.2079(9) 0.000 1 4 Biso 0.489585
O2 O 0.5016(12) 0.0481(12) -0.1155(5) 1 8 Biso 0.489585
O3 O 0.4528(9) 0.4528(9) 0.000 1 4 Biso 0.489585


loop_
_geom_bond_atom_site_label_1
_geom_bond_atom_site_label_2
_geom_bond_distance
_geom_bond_site_symmetry_1
_geom_bond_site_symmetry_2
_geom_bond_publ_flag
O(1) C(1) 1.226(7) . . no
O(2) C(2) 1.216(9) . . no
O(3) C(3) 1.193(7) . . no
N(1) C(1) 1.383(6) . . no
N(1) C(2) 1.365(8) . . no
C(2) C(3) 1.520(7) . . no
N(1) H(1) 1.132(8) . . no
N(1) D(1) 1.032(8) . . no


loop_
_geom_angle_atom_site_label_1
_geom_angle_atom_site_label_2
_geom_angle_atom_site_label_3
_geom_angle
_geom_angle_site_symmetry_1
_geom_angle_site_symmetry_2
_geom_angle_site_symmetry_3
_geom_angle_publ_flag
C(1) N(1) C(2) 126.4(5) . . . no
O(1) C(1) N(1) 121.2(4) . . . no
O(1) C(1) N(1) 121.2(4) . . . no
N(1) C(1) N(1) 117.6(5) . . . no
O(2) C(2) N(1) 122.1(6) . . . no
O(2) C(2) C(3) 122.2(6) . . . no
N(1) C(2) C(3) 115.7(4) . . . no
O(3) C(3) C(2) 120.8(4) . . . no
O(3) C(3) C(2) 120.8(4) . . . no
C(2) C(3) C(2) 118.4(4) . . . no
C(1) N(1) H(1) 116.8(6) . . . no
C(1) N(1) D(1) 116.8(6) . . . no
C(2) N(1) H(1) 116.8(5) . . . no
C(2) N(1) D(1) 116.8(6) . . . no


loop_
_geom_torsion_atom_site_label_1
_geom_torsion_atom_site_label_2
_geom_torsion_atom_site_label_3
_geom_torsion_atom_site_label_4
_geom_torsion
_geom_torsion_site_symmetry_1
_geom_torsion_site_symmetry_2
_geom_torsion_site_symmetry_3
_geom_torsion_site_symmetry_4
_geom_torsion_publ_flag
C(2) N(1) C(1) O(1) 180.0(4) . . . . no
C(2) N(1) C(1) N(1) 0.0(6) . . . . no
C(1) N(1) C(2) O(2) 180.0(5) . . . . no
C(1) N(1) C(2) C(3) 0.0(7) . . . . no
O(2) C(2) C(3) O(3) 0.0(7) . . . . no
O(2) C(2) C(3) C(2) 180.0(5) . . . . no
N(1) C(2) C(3) O(3) 180.0(4) . . . . no
N(1) C(2) C(3) C(2) 0.0(6) . . . . no
H(1) N(1) C(1) O(1) 0.0(7) . . . . no
H(1) N(1) C(1) N(1) 180.0(5) . . . . no
H(1) N(1) C(2) O(2) 0.0(8) . . . . no
H(1) N(1) C(2) C(3) 180.0(5) . . . . no
_exptl_crystal_colour            yellow
_symmetry_space_group_name_H-M   P41212
####################################################################### 
# 
# This file contains crystal structure data downloaded from the 
# Cambridge Structural Database (CSD) hosted by the Cambridge 
# Crystallographic Data Centre (CCDC).
# 
# Full information about CCDC data access policies and citation 
# guidelines are available at http://www.ccdc.cam.ac.uk/access/V1 
# 
# Audit and citation data items may have been added by the CCDC. 
# Please retain this information to preserve the provenance of 
# this file and to allow appropriate attribution of the data. 
# 
#######################################################################

data_Alloxan_1p92GPa
_database_code_depnum_ccdc_archive 'CCDC 1994631'
loop_
_audit_author_name
_audit_author_address
'Nicholas Funnell'
;STFC, ISIS Neutron Facility
United Kingdom
;
_audit_update_record             
;
2020-04-03 deposited with the CCDC.	2020-05-01 downloaded from the CCDC.
;
# start Validation Reply Form
_vrf_PLAT699_Alloxan_1p92GPa     
;
PROBLEM: Missing _exptl_crystal_description Value .......     Please Do !
RESPONSE: Not applicable - powder sample.
;
_vrf_PLAT430_Alloxan_1p92GPa     
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.71 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT041_Alloxan_1p92GPa     
;
PROBLEM: Calc. and Reported SumFormula    Strings  Differ     Please Check
RESPONSE: This is possibly an erroneous alert? The calculated and reported formulae appear to be the same.
;
_vrf_PLAT340_Alloxan_1p92GPa     
;
PROBLEM: Low Bond Precision on  C-C Bonds ...............      0.006 Ang.
RESPONSE: The structure is refined against high-pressure data which suffer from higher signal-to-noise and lower peak resolution that standard powder patterns. Direct refinement of the atomic coordinates is not possible and so the molecular geometry is constrained via a rigid body. This has all led to the low bond precision seen here.
;

_chemical_name_systematic        pyrimidine-2,4,5,6-tetraone
_chemical_name_common            alloxan
_chemical_formula_moiety         'C4 O4 N2 H1.50 D0.50'
_chemical_formula_structural     'C4 O4 N2 H1.50 D0.50'
_chemical_formula_sum            'C4 O4 N2 H1.50 D0.50'
_chemical_formula_weight         142.58
_chemical_compound_source        Sigma-Aldrich

_space_group_crystal_system      Tetragonal
_symmetry_space_group_name_Hall  'P 4abw 2nw'
_space_group_name_H-M            P41212
_symmetry_Int_Tables_number      92

loop_
_symmetry_equiv_pos_as_xyz
'x, y, z '
'-x+1/2, y+1/2, -z+1/4 '
'-y, -x, -z+1/2 '
'-y+1/2, x+1/2, z+1/4 '
'y, x, -z '
'y+1/2, -x+1/2, z-1/4 '
'-x, -y, z+1/2 '
'x+1/2, -y+1/2, -z-1/4 '

_cell_length_a                   5.7051(6)
_cell_length_b                   5.7051(6)
_cell_length_c                   13.6603(17)
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_volume                     444.62(10)
_cell_formula_units_Z            4

_cell_measurement_temperature    293.00000
_cell_measurement_pressure       1.92173 #GPa

_cell_special_details            
;
Cell parameters included in refinement
;

_exptl_crystal_density_diffrn    2.130

_pd_spec_mounting                'TiZr Capsule'
_pd_spec_mount_mode              transmission
_pd_char_colour                  yellow
_chemical_absolute_configuration .

_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details   
;
Calculated using MANTID routines.
;

_pd_instr_location               
'ISIS Neutron Facility. Rutherford Appleton Laboratory'
_diffrn_ambient_temperature      293.00000
_diffrn_source                   'Pulsed neutron source'
_diffrn_source_target            W
_diffrn_radiation_type           Neutron
_diffrn_measurement_device_type  'PEARL diffractometer'
_diffrn_radiation_monochromator  none
_diffrn_detector                 'ZnS scintillator'
_diffrn_detector_type            custom

_pd_meas_scan_method             Time-of-flight
_pd_meas_special_details         
;
Time of flight method using a pulsed neutron source
;

# The following three items are used for time-of-flight measurements only.
_pd_instr_dist_src/spec          12800
_pd_instr_dist_spec/detc         800
_pd_meas_2theta_fixed            90

_pr_proc_ls_profile_function     
;
Voigt function convoluted with a back-to-back double exponential.
;

_pd_proc_ls_background_function  'Chebychev polynomial'

_pd_proc_ls_pref_orient_corr     
;
No requirement for preferred orientation correction
;

_refine_ls_goodness_of_fit_all   0.91772
_pd_proc_ls_prof_R_factor        2.54328
_pd_proc_ls_prof_wR_factor       2.53937
_pd_proc_ls_prof_wR_expected     2.76704
_refine_ls_R_I_factor            2.16516
_refine_ls_matrix_type           sparse
_refine_ls_weighting_scheme      sigma
_refine_ls_weighting_details     ?
_refine_ls_hydrogen_treatment    ?
_refine_ls_extinction_method     none
_refine_ls_number_parameters     42
_refine_ls_number_restraints     ?
_refine_ls_number_constraints    ?
_refine_diff_density_max         ?
_refine_diff_density_min         ?
_refine_ls_shift/su_max          <0.01


_pd_proc_info_data_reduction     
;
Data reduction performed using Mantid
;

_refine_special_details          
;
The molecular structure is refined via a rigid body Z-matrix. All 
intramolecular geometry is constrained to the values determined from 
high-resolution powder neutron data (ALOXAN14). These parameters are not
expected to change with pressure.

Refinements show that the sample is only partially deuterated. H and D atoms 
sites were both included in the refinement, where an overall H/D occupancy is 
refined against all data.

Isotropic displacement parameters for C and N atoms are allowed to refine for 
lower-pressure structures. Parameters for the O and D/H atoms were fixed at 
1.5x the value of the parent atoms, due to unstable refinement - these ratios 
are informed by the approximate values obtained when refining against a 
preliminary data collection carried out in a vanadium can (not reported). Above
approximately 3 GPa, no displacement parameters could be stably refined, so 
they were then held fixed to the last stably-refined values.

The number of parameters quoted in the CIFs for each pressure point, includes 9
background terms and 23 parameters corresponding to contaminant phases (WC, Ni 
and Pb) which arise from the sample environment. Alloxan accounts for 10 of the
number of parameters quoted.

Sample pressures are determined using the refined lead lattice parameter and a 
Birch-Murnaghan equation of state.
;


#CHECK-CIF ALERTS


loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_symmetry_multiplicity
_atom_site_adp_type
_atom_site_B_iso_or_equiv
H1 H 0.1615(10) -0.2422(10) -0.1019(4) 0.748(6) 8 Biso 0.45(19)
D1 D 0.1601(10) -0.2277(10) -0.0979(4) 0.252(6) 8 Biso 0.45(19)
N1 N 0.1454(9) -0.0774(9) -0.0563(2) 1 8 Biso 0.30(12)
C1 C -0.0548(8) -0.0548(8) 0.000 1 4 Biso 0.17(7)
C2 C 0.3254(9) 0.0794(9) -0.0621(3) 1 8 Biso 0.17(7)
C3 C 0.2990(8) 0.2990(8) 0.000 1 4 Biso 0.17(7)
O1 O -0.2067(8) -0.2067(8) 0.000 1 4 Biso 0.25(11)
O2 O 0.4959(10) 0.0458(10) -0.1137(5) 1 8 Biso 0.25(11)
O3 O 0.4470(8) 0.4470(8) 0.000 1 4 Biso 0.25(11)


loop_
_geom_bond_atom_site_label_1
_geom_bond_atom_site_label_2
_geom_bond_distance
_geom_bond_site_symmetry_1
_geom_bond_site_symmetry_2
_geom_bond_publ_flag
O(1) C(1) 1.226(6) . . no
O(2) C(2) 1.217(8) . . no
O(3) C(3) 1.194(6) . . no
N(1) C(1) 1.383(6) . . no
N(1) C(2) 1.364(7) . . no
C(2) C(3) 1.521(6) . . no
N(1) H(1) 1.132(7) . . no
N(1) D(1) 1.032(7) . . no


loop_
_geom_angle_atom_site_label_1
_geom_angle_atom_site_label_2
_geom_angle_atom_site_label_3
_geom_angle
_geom_angle_site_symmetry_1
_geom_angle_site_symmetry_2
_geom_angle_site_symmetry_3
_geom_angle_publ_flag
C(1) N(1) C(2) 126.4(4) . . . no
O(1) C(1) N(1) 121.2(4) . . . no
O(1) C(1) N(1) 121.2(4) . . . no
N(1) C(1) N(1) 117.6(4) . . . no
O(2) C(2) N(1) 122.2(5) . . . no
O(2) C(2) C(3) 122.2(5) . . . no
N(1) C(2) C(3) 115.7(4) . . . no
O(3) C(3) C(2) 120.8(4) . . . no
O(3) C(3) C(2) 120.8(4) . . . no
C(2) C(3) C(2) 118.3(4) . . . no
C(1) N(1) H(1) 116.8(5) . . . no
C(1) N(1) D(1) 116.8(6) . . . no
C(2) N(1) H(1) 116.9(5) . . . no
C(2) N(1) D(1) 116.9(5) . . . no



loop_
_geom_torsion_atom_site_label_1
_geom_torsion_atom_site_label_2
_geom_torsion_atom_site_label_3
_geom_torsion_atom_site_label_4
_geom_torsion
_geom_torsion_site_symmetry_1
_geom_torsion_site_symmetry_2
_geom_torsion_site_symmetry_3
_geom_torsion_site_symmetry_4
_geom_torsion_publ_flag
C(2) N(1) C(1) O(1) 180.0(4) . . . . no
C(2) N(1) C(1) N(1) 0.0(6) . . . . no
C(1) N(1) C(2) O(2) 180.0(5) . . . . no
C(1) N(1) C(2) C(3) 0.1(6) . . . . no
O(2) C(2) C(3) O(3) 0.0(7) . . . . no
O(2) C(2) C(3) C(2) 180.0(5) . . . . no
N(1) C(2) C(3) O(3) 180.0(4) . . . . no
N(1) C(2) C(3) C(2) 0.0(5) . . . . no
H(1) N(1) C(1) O(1) 0.1(6) . . . . no
H(1) N(1) C(1) N(1) 179.9(5) . . . . no
H(1) N(1) C(2) O(2) 0.1(8) . . . . no
H(1) N(1) C(2) C(3) 180.0(4) . . . . no
_exptl_crystal_colour            yellow
_symmetry_space_group_name_H-M   P41212
####################################################################### 
# 
# This file contains crystal structure data downloaded from the 
# Cambridge Structural Database (CSD) hosted by the Cambridge 
# Crystallographic Data Centre (CCDC).
# 
# Full information about CCDC data access policies and citation 
# guidelines are available at http://www.ccdc.cam.ac.uk/access/V1 
# 
# Audit and citation data items may have been added by the CCDC. 
# Please retain this information to preserve the provenance of 
# this file and to allow appropriate attribution of the data. 
# 
#######################################################################

data_Alloxan_2p41GPa
_database_code_depnum_ccdc_archive 'CCDC 1994632'
loop_
_audit_author_name
_audit_author_address
'Nicholas Funnell'
;STFC, ISIS Neutron Facility
United Kingdom
;
_audit_update_record             
;
2020-04-03 deposited with the CCDC.	2020-05-01 downloaded from the CCDC.
;
# start Validation Reply Form
_vrf_PLAT699_Alloxan_2p41GPa     
;
PROBLEM: Missing _exptl_crystal_description Value .......     Please Do !
RESPONSE: Not applicable - powder sample.
;
_vrf_PLAT430_Alloxan_2p41GPa     
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.69 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT041_Alloxan_2p41GPa     
;
PROBLEM: Calc. and Reported SumFormula    Strings  Differ     Please Check
RESPONSE: This is possibly an erroneous alert? The calculated and reported formulae appear to be the same.
;
_vrf_PLAT340_Alloxan_2p41GPa     
;
PROBLEM: Low Bond Precision on  C-C Bonds ...............      0.009 Ang.
RESPONSE: The structure is refined against high-pressure data which suffer from higher signal-to-noise and lower peak resolution that standard powder patterns. Direct refinement of the atomic coordinates is not possible and so the molecular geometry is constrained via a rigid body. This has all led to the low bond precision seen here.
;

_chemical_name_systematic        pyrimidine-2,4,5,6-tetraone
_chemical_name_common            alloxan
_chemical_formula_moiety         'C4 O4 N2 H1.50 D0.50'
_chemical_formula_structural     'C4 O4 N2 H1.50 D0.50'
_chemical_formula_sum            'C4 O4 N2 H1.50 D0.50'
_chemical_formula_weight         142.58
_chemical_compound_source        Sigma-Aldrich

_space_group_crystal_system      Tetragonal
_symmetry_space_group_name_Hall  'P 4abw 2nw'
_space_group_name_H-M            P41212
_symmetry_Int_Tables_number      92

loop_
_symmetry_equiv_pos_as_xyz
'x, y, z '
'-x+1/2, y+1/2, -z+1/4 '
'-y, -x, -z+1/2 '
'-y+1/2, x+1/2, z+1/4 '
'y, x, -z '
'y+1/2, -x+1/2, z-1/4 '
'-x, -y, z+1/2 '
'x+1/2, -y+1/2, -z-1/4 '

_cell_length_a                   5.6753(10)
_cell_length_b                   5.6753(10)
_cell_length_c                   13.593(3)
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_volume                     437.84(17)
_cell_formula_units_Z            4

_cell_measurement_temperature    293.00000
_cell_measurement_pressure       2.40666 #GPa

_cell_special_details            
;
Cell parameters included in refinement
;

_exptl_crystal_density_diffrn    2.163

_pd_spec_mounting                'TiZr Capsule'
_pd_spec_mount_mode              transmission
_pd_char_colour                  yellow
_chemical_absolute_configuration .

_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details   
;
Calculated using MANTID routines.
;

_pd_instr_location               
'ISIS Neutron Facility. Rutherford Appleton Laboratory'
_diffrn_ambient_temperature      293.00000
_diffrn_source                   'Pulsed neutron source'
_diffrn_source_target            W
_diffrn_radiation_type           Neutron
_diffrn_measurement_device_type  'PEARL diffractometer'
_diffrn_radiation_monochromator  none
_diffrn_detector                 'ZnS scintillator'
_diffrn_detector_type            custom

_pd_meas_scan_method             Time-of-flight
_pd_meas_special_details         
;
Time of flight method using a pulsed neutron source
;

# The following three items are used for time-of-flight measurements only.
_pd_instr_dist_src/spec          12800
_pd_instr_dist_spec/detc         800
_pd_meas_2theta_fixed            90

_pr_proc_ls_profile_function     
;
Voigt function convoluted with a back-to-back double exponential.
;

_pd_proc_ls_background_function  'Chebychev polynomial'

_pd_proc_ls_pref_orient_corr     
;
No requirement for preferred orientation correction
;

_refine_ls_goodness_of_fit_all   0.82697
_pd_proc_ls_prof_R_factor        3.32849
_pd_proc_ls_prof_wR_factor       3.27642
_pd_proc_ls_prof_wR_expected     3.96195
_refine_ls_R_I_factor            1.41142
_refine_ls_matrix_type           sparse
_refine_ls_weighting_scheme      sigma
_refine_ls_weighting_details     ?
_refine_ls_hydrogen_treatment    ?
_refine_ls_extinction_method     none
_refine_ls_number_parameters     42
_refine_ls_number_restraints     ?
_refine_ls_number_constraints    ?
_refine_diff_density_max         ?
_refine_diff_density_min         ?
_refine_ls_shift/su_max          <0.01

_pd_proc_info_data_reduction     
;
Data reduction performed using Mantid
;

_refine_special_details          
;
The molecular structure is refined via a rigid body Z-matrix. All 
intramolecular geometry is constrained to the values determined from 
high-resolution powder neutron data (ALOXAN14). These parameters are not
expected to change with pressure.

Refinements show that the sample is only partially deuterated. H and D atoms 
sites were both included in the refinement, where an overall H/D occupancy is 
refined against all data.

Isotropic displacement parameters for C and N atoms are allowed to refine for 
lower-pressure structures. Parameters for the O and D/H atoms were fixed at 
1.5x the value of the parent atoms, due to unstable refinement - these ratios 
are informed by the approximate values obtained when refining against a 
preliminary data collection carried out in a vanadium can (not reported). Above
approximately 3 GPa, no displacement parameters could be stably refined, so 
they were then held fixed to the last stably-refined values.

The number of parameters quoted in the CIFs for each pressure point, includes 9
background terms and 23 parameters corresponding to contaminant phases (WC, Ni 
and Pb) which arise from the sample environment. Alloxan accounts for 10 of the
number of parameters quoted.

Sample pressures are determined using the refined lead lattice parameter and a 
Birch-Murnaghan equation of state.
;


#CHECK-CIF ALERTS


loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_symmetry_multiplicity
_atom_site_adp_type
_atom_site_B_iso_or_equiv
H1 H 0.1629(15) -0.2435(15) -0.1023(6) 0.748(6) 8 Biso 0.4(3)
D1 D 0.1615(15) -0.2288(15) -0.0982(6) 0.252(6) 8 Biso 0.4(3)
N1 N 0.1466(13) -0.0776(13) -0.0564(3) 1 8 Biso 0.24(18)
C1 C -0.0548(12) -0.0548(12) 0.000 1 4 Biso 0.32(12)
C2 C 0.3276(13) 0.0800(13) -0.0623(4) 1 8 Biso 0.32(12)
C3 C 0.3008(12) 0.3008(12) 0.000 1 4 Biso 0.32(12)
O1 O -0.2075(12) -0.2075(12) 0.000 1 4 Biso 0.48(18)
O2 O 0.4991(16) 0.0460(16) -0.1140(7) 1 8 Biso 0.48(18)
O3 O 0.4496(12) 0.4496(12) 0.000 1 4 Biso 0.48(18)



loop_
_geom_bond_atom_site_label_1
_geom_bond_atom_site_label_2
_geom_bond_distance
_geom_bond_site_symmetry_1
_geom_bond_site_symmetry_2
_geom_bond_publ_flag
O(1) C(1) 1.226(10) . . no
O(2) C(2) 1.216(11) . . no
O(3) C(3) 1.194(10) . . no
N(1) C(1) 1.382(9) . . no
N(1) C(2) 1.364(10) . . no
C(2) C(3) 1.520(9) . . no
N(1) H(1) 1.133(11) . . no
N(1) D(1) 1.033(11) . . no


loop_
_geom_angle_atom_site_label_1
_geom_angle_atom_site_label_2
_geom_angle_atom_site_label_3
_geom_angle
_geom_angle_site_symmetry_1
_geom_angle_site_symmetry_2
_geom_angle_site_symmetry_3
_geom_angle_publ_flag
C(1) N(1) C(2) 126.4(6) . . . no
O(1) C(1) N(1) 121.2(6) . . . no
O(1) C(1) N(1) 121.2(6) . . . no
N(1) C(1) N(1) 117.5(6) . . . no
O(2) C(2) N(1) 122.2(7) . . . no
O(2) C(2) C(3) 122.2(7) . . . no
N(1) C(2) C(3) 115.6(6) . . . no
O(3) C(3) C(2) 120.8(6) . . . no
O(3) C(3) C(2) 120.8(6) . . . no
C(2) C(3) C(2) 118.4(6) . . . no
C(1) N(1) H(1) 116.8(8) . . . no
C(1) N(1) D(1) 116.8(8) . . . no
C(2) N(1) H(1) 116.8(7) . . . no
C(2) N(1) D(1) 116.8(8) . . . no



loop_
_geom_torsion_atom_site_label_1
_geom_torsion_atom_site_label_2
_geom_torsion_atom_site_label_3
_geom_torsion_atom_site_label_4
_geom_torsion
_geom_torsion_site_symmetry_1
_geom_torsion_site_symmetry_2
_geom_torsion_site_symmetry_3
_geom_torsion_site_symmetry_4
_geom_torsion_publ_flag
C(2) N(1) C(1) O(1) 180.0(6) . . . . no
C(2) N(1) C(1) N(1) 0.0(9) . . . . no
C(1) N(1) C(2) O(2) 180.0(7) . . . . no
C(1) N(1) C(2) C(3) 0.0(9) . . . . no
O(2) C(2) C(3) O(3) 0.0(10) . . . . no
O(2) C(2) C(3) C(2) 180.0(7) . . . . no
N(1) C(2) C(3) O(3) 180.0(5) . . . . no
N(1) C(2) C(3) C(2) 0.0(7) . . . . no
H(1) N(1) C(1) O(1) 0.0(9) . . . . no
H(1) N(1) C(1) N(1) 180.0(7) . . . . no
H(1) N(1) C(2) O(2) 0.0(11) . . . . no
H(1) N(1) C(2) C(3) 180.0(7) . . . . no
_exptl_crystal_colour            yellow
_symmetry_space_group_name_H-M   P41212
####################################################################### 
# 
# This file contains crystal structure data downloaded from the 
# Cambridge Structural Database (CSD) hosted by the Cambridge 
# Crystallographic Data Centre (CCDC).
# 
# Full information about CCDC data access policies and citation 
# guidelines are available at http://www.ccdc.cam.ac.uk/access/V1 
# 
# Audit and citation data items may have been added by the CCDC. 
# Please retain this information to preserve the provenance of 
# this file and to allow appropriate attribution of the data. 
# 
#######################################################################

data_Alloxan_4p33GPa
_database_code_depnum_ccdc_archive 'CCDC 1994634'
loop_
_audit_author_name
_audit_author_address
'Nicholas Funnell'
;STFC, ISIS Neutron Facility
United Kingdom
;
_audit_update_record             
;
2020-04-03 deposited with the CCDC.	2020-05-01 downloaded from the CCDC.
;
# start Validation Reply Form
_vrf_PLAT699_Alloxan_4p33GPa     
;
PROBLEM: Missing _exptl_crystal_description Value .......     Please Do !
RESPONSE: Not applicable - powder sample.
;
_vrf_PLAT430_Alloxan_4p33GPa     
;
PROBLEM: Short Inter D...A Contact  O1       ..O3       .       2.65 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT430_Alloxan_4p33GPa_2   
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.67 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT430_Alloxan_4p33GPa_3   
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.67 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT041_Alloxan_4p33GPa     
;
PROBLEM: Calc. and Reported SumFormula    Strings  Differ     Please Check
RESPONSE: This is possibly an erroneous alert? The calculated and reported formulae appear to be the same.
;
_vrf_PLAT340_Alloxan_4p33GPa     
;
PROBLEM: Low Bond Precision on  C-C Bonds ...............      0.007 Ang.
RESPONSE: The structure is refined against high-pressure data which suffer from higher signal-to-noise and lower peak resolution that standard powder patterns. Direct refinement of the atomic coordinates is not possible and so the molecular geometry is constrained via a rigid body. This has all led to the low bond precision seen here.
;
_vrf_PLAT430_Alloxan_4p33GPa_4   
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.89 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT430_Alloxan_4p33GPa_5   
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.89 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;

_chemical_name_systematic        pyrimidine-2,4,5,6-tetraone
_chemical_name_common            alloxan
_chemical_formula_moiety         'C4 O4 N2 H1.50 D0.50'
_chemical_formula_structural     'C4 O4 N2 H1.50 D0.50'
_chemical_formula_sum            'C4 O4 N2 H1.50 D0.50'
_chemical_formula_weight         142.58
_chemical_compound_source        Sigma-Aldrich

_space_group_crystal_system      Tetragonal
_symmetry_space_group_name_Hall  'P 4abw 2nw'
_space_group_name_H-M            P41212
_symmetry_Int_Tables_number      92

loop_
_symmetry_equiv_pos_as_xyz
'x, y, z '
'-x+1/2, y+1/2, -z+1/4 '
'-y, -x, -z+1/2 '
'-y+1/2, x+1/2, z+1/4 '
'y, x, -z '
'y+1/2, -x+1/2, z-1/4 '
'-x, -y, z+1/2 '
'x+1/2, -y+1/2, -z-1/4 '

_cell_length_a                   5.5997(10)
_cell_length_b                   5.5997(10)
_cell_length_c                   13.351(3)
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_volume                     418.64(18)
_cell_formula_units_Z            4

_cell_measurement_temperature    293.00000
_cell_measurement_pressure       4.33309 #GPa

_cell_special_details            
;
Cell parameters included in refinement
;

_exptl_crystal_density_diffrn    2.262

_pd_spec_mounting                'TiZr Capsule'
_pd_spec_mount_mode              transmission
_pd_char_colour                  yellow
_chemical_absolute_configuration .

_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details   
;
Calculated using MANTID routines.
;

_pd_instr_location               
'ISIS Neutron Facility. Rutherford Appleton Laboratory'
_diffrn_ambient_temperature      293.00000
_diffrn_source                   'Pulsed neutron source'
_diffrn_source_target            W
_diffrn_radiation_type           Neutron
_diffrn_measurement_device_type  'PEARL diffractometer'
_diffrn_radiation_monochromator  none
_diffrn_detector                 'ZnS scintillator'
_diffrn_detector_type            custom

_pd_meas_scan_method             Time-of-flight
_pd_meas_special_details         
;
Time of flight method using a pulsed neutron source
;

# The following three items are used for time-of-flight measurements only.
_pd_instr_dist_src/spec          12800
_pd_instr_dist_spec/detc         800
_pd_meas_2theta_fixed            90

_pr_proc_ls_profile_function     
;
Voigt function convoluted with a back-to-back double exponential.
;

_pd_proc_ls_background_function  'Chebychev polynomial'

_pd_proc_ls_pref_orient_corr     
;
No requirement for preferred orientation correction
;

_refine_ls_goodness_of_fit_all   0.97468
_pd_proc_ls_prof_R_factor        2.69863
_pd_proc_ls_prof_wR_factor       2.71568
_pd_proc_ls_prof_wR_expected     2.78621
_refine_ls_R_I_factor            2.06001
_refine_ls_matrix_type           sparse
_refine_ls_weighting_scheme      sigma
_refine_ls_weighting_details     ?
_refine_ls_hydrogen_treatment    ?
_refine_ls_extinction_method     none
_refine_ls_number_parameters     40
_refine_ls_number_restraints     ?
_refine_ls_number_constraints    ?
_refine_diff_density_max         ?
_refine_diff_density_min         ?
_refine_ls_shift/su_max          <0.01


_pd_proc_info_data_reduction     
;
Data reduction performed using Mantid
;

_refine_special_details          
;
The molecular structure is refined via a rigid body Z-matrix. All 
intramolecular geometry is constrained to the values determined from 
high-resolution powder neutron data (ALOXAN14). These parameters are not
expected to change with pressure.

Refinements show that the sample is only partially deuterated. H and D atoms 
sites were both included in the refinement, where an overall H/D occupancy is 
refined against all data.

Isotropic displacement parameters for C and N atoms are allowed to refine for 
lower-pressure structures. Parameters for the O and D/H atoms were fixed at 
1.5x the value of the parent atoms, due to unstable refinement - these ratios 
are informed by the approximate values obtained when refining against a 
preliminary data collection carried out in a vanadium can (not reported). Above
approximately 3 GPa, no displacement parameters could be stably refined, so 
they were then held fixed to the last stably-refined values.

The number of parameters quoted in the CIFs for each pressure point, includes 9
background terms and 23 parameters corresponding to contaminant phases (WC, Ni 
and Pb) which arise from the sample environment. Alloxan accounts for 8 of the
number of parameters quoted.

Sample pressures are determined using the refined lead lattice parameter and a 
Birch-Murnaghan equation of state.
;


#CHECK-CIF ALERTS



loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_symmetry_multiplicity
_atom_site_adp_type
_atom_site_B_iso_or_equiv
H1 H 0.1684(13) -0.2392(13) -0.1056(5) 0.748(6) 8 Biso 0.36426
D1 D 0.1670(12) -0.2245(12) -0.1014(5) 0.252(6) 8 Biso 0.36426
N1 N 0.1528(11) -0.0721(11) -0.0583(3) 1 8 Biso 0.24284
C1 C -0.0501(10) -0.0501(10) 0.000 1 4 Biso 0.32639
C2 C 0.3361(11) 0.0877(11) -0.0643(3) 1 8 Biso 0.32639
C3 C 0.3103(10) 0.3103(10) 0.000 1 4 Biso 0.32639
O1 O -0.2049(10) -0.2049(10) 0.000 1 4 Biso 0.489585
O2 O 0.5088(13) 0.0544(13) -0.1177(6) 1 8 Biso 0.489585
O3 O 0.4610(10) 0.4610(10) 0.000 1 4 Biso 0.489585


loop_
_geom_bond_atom_site_label_1
_geom_bond_atom_site_label_2
_geom_bond_distance
_geom_bond_site_symmetry_1
_geom_bond_site_symmetry_2
_geom_bond_publ_flag
O(1) C(1) 1.226(8) . . no
O(2) C(2) 1.216(9) . . no
O(3) C(3) 1.193(8) . . no
N(1) C(1) 1.383(7) . . no
N(1) C(2) 1.364(9) . . no
C(2) C(3) 1.520(7) . . no
N(1) H(1) 1.132(9) . . no
N(1) D(1) 1.032(9) . . no


loop_
_geom_angle_atom_site_label_1
_geom_angle_atom_site_label_2
_geom_angle_atom_site_label_3
_geom_angle
_geom_angle_site_symmetry_1
_geom_angle_site_symmetry_2
_geom_angle_site_symmetry_3
_geom_angle_publ_flag
C(1) N(1) C(2) 126.4(5) . . . no
O(1) C(1) N(1) 121.2(5) . . . no
O(1) C(1) N(1) 121.2(5) . . . no
N(1) C(1) N(1) 117.6(5) . . . no
O(2) C(2) N(1) 122.2(6) . . . no
O(2) C(2) C(3) 122.2(6) . . . no
N(1) C(2) C(3) 115.7(5) . . . no
O(3) C(3) C(2) 120.8(5) . . . no
O(3) C(3) C(2) 120.8(5) . . . no
C(2) C(3) C(2) 118.3(5) . . . no
C(1) N(1) H(1) 116.8(6) . . . no
C(1) N(1) D(1) 116.8(7) . . . no
C(2) N(1) H(1) 116.8(6) . . . no
C(2) N(1) D(1) 116.9(6) . . . no


loop_
_geom_torsion_atom_site_label_1
_geom_torsion_atom_site_label_2
_geom_torsion_atom_site_label_3
_geom_torsion_atom_site_label_4
_geom_torsion
_geom_torsion_site_symmetry_1
_geom_torsion_site_symmetry_2
_geom_torsion_site_symmetry_3
_geom_torsion_site_symmetry_4
_geom_torsion_publ_flag
C(2) N(1) C(1) O(1) 180.0(5) . . . . no
C(2) N(1) C(1) N(1) 0.0(7) . . . . no
C(1) N(1) C(2) O(2) 180.0(6) . . . . no
C(1) N(1) C(2) C(3) 0.1(7) . . . . no
O(2) C(2) C(3) O(3) 0.0(8) . . . . no
O(2) C(2) C(3) C(2) 180.0(6) . . . . no
N(1) C(2) C(3) O(3) 180.0(4) . . . . no
N(1) C(2) C(3) C(2) 0.0(6) . . . . no
H(1) N(1) C(1) O(1) 0.0(8) . . . . no
H(1) N(1) C(1) N(1) 180.0(6) . . . . no
H(1) N(1) C(2) O(2) 0.1(9) . . . . no
H(1) N(1) C(2) C(3) 180.0(6) . . . . no
_exptl_crystal_colour            yellow
_symmetry_space_group_name_H-M   P41212
####################################################################### 
# 
# This file contains crystal structure data downloaded from the 
# Cambridge Structural Database (CSD) hosted by the Cambridge 
# Crystallographic Data Centre (CCDC).
# 
# Full information about CCDC data access policies and citation 
# guidelines are available at http://www.ccdc.cam.ac.uk/access/V1 
# 
# Audit and citation data items may have been added by the CCDC. 
# Please retain this information to preserve the provenance of 
# this file and to allow appropriate attribution of the data. 
# 
#######################################################################

data_Alloxan_1p16GPa
_database_code_depnum_ccdc_archive 'CCDC 1994629'
loop_
_audit_author_name
_audit_author_address
'Nicholas Funnell'
;STFC, ISIS Neutron Facility
United Kingdom
;
_audit_update_record             
;
2020-04-03 deposited with the CCDC.	2020-05-01 downloaded from the CCDC.
;
# start Validation Reply Form
_vrf_PLAT699_Alloxan_1p16GPa     
;
PROBLEM: Missing _exptl_crystal_description Value .......     Please Do !
RESPONSE: Not applicable - powder sample.
;
_vrf_PLAT430_Alloxan_1p16GPa     
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.75 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT430_Alloxan_1p16GPa_2   
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.75 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT041_Alloxan_1p16GPa     
;
PROBLEM: Calc. and Reported SumFormula    Strings  Differ     Please Check
RESPONSE: This is possibly an erroneous alert? The calculated and reported formulae appear to be the same.
;
_vrf_PLAT340_Alloxan_1p16GPa     
;
PROBLEM: Low Bond Precision on  C-C Bonds ...............      0.007 Ang.
RESPONSE: The structure is refined against high-pressure data which suffer from higher signal-to-noise and lower peak resolution that standard powder patterns. Direct refinement of the atomic coordinates is not possible and so the molecular geometry is constrained via a rigid body. This has all led to the low bond precision seen here.
;
_vrf_PLAT430_Alloxan_1p16GPa_3   
;
PROBLEM: Short Inter D...A Contact  O1       ..O3       .       2.87 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;

_chemical_name_systematic        pyrimidine-2,4,5,6-tetraone
_chemical_name_common            alloxan
_chemical_formula_moiety         'C4 O4 N2 H1.50 D0.50'
_chemical_formula_structural     'C4 O4 N2 H1.50 D0.50'
_chemical_formula_sum            'C4 O4 N2 H1.50 D0.50'
_chemical_formula_weight         142.58
_chemical_compound_source        Sigma-Aldrich

_space_group_crystal_system      Tetragonal
_symmetry_space_group_name_Hall  'P 4abw 2nw'
_space_group_name_H-M            P41212
_symmetry_Int_Tables_number      92

loop_
_symmetry_equiv_pos_as_xyz
'x, y, z '
'-x+1/2, y+1/2, -z+1/4 '
'-y, -x, -z+1/2 '
'-y+1/2, x+1/2, z+1/4 '
'y, x, -z '
'y+1/2, -x+1/2, z-1/4 '
'-x, -y, z+1/2 '
'x+1/2, -y+1/2, -z-1/4 '

_cell_length_a                   5.7580(7)
_cell_length_b                   5.7580(7)
_cell_length_c                   13.794(2)
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_volume                     457.33(14)
_cell_formula_units_Z            4

_cell_measurement_temperature    293.00000
_cell_measurement_pressure       1.16279 #GPa

_cell_special_details            
;
Cell parameters included in refinement
;

_exptl_crystal_density_diffrn    2.071

_pd_spec_mounting                'TiZr Capsule'
_pd_spec_mount_mode              transmission
_pd_char_colour                  yellow
_chemical_absolute_configuration .

_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details   
;
Calculated using MANTID routines.
;

_pd_instr_location               
'ISIS Neutron Facility. Rutherford Appleton Laboratory'
_diffrn_ambient_temperature      293.00000
_diffrn_source                   'Pulsed neutron source'
_diffrn_source_target            W
_diffrn_radiation_type           Neutron
_diffrn_measurement_device_type  'PEARL diffractometer'
_diffrn_radiation_monochromator  none
_diffrn_detector                 'ZnS scintillator'
_diffrn_detector_type            custom

_pd_meas_scan_method             Time-of-flight
_pd_meas_special_details         
;
Time of flight method using a pulsed neutron source
;

# The following three items are used for time-of-flight measurements only.
_pd_instr_dist_src/spec          12800
_pd_instr_dist_spec/detc         800
_pd_meas_2theta_fixed            90

_pr_proc_ls_profile_function     
;
Voigt function convoluted with a back-to-back double exponential.
;

_pd_proc_ls_background_function  'Chebychev polynomial'

_pd_proc_ls_pref_orient_corr     
;
No requirement for preferred orientation correction
;

_refine_ls_goodness_of_fit_all   0.82313
_pd_proc_ls_prof_R_factor        3.22599
_pd_proc_ls_prof_wR_factor       3.16962
_pd_proc_ls_prof_wR_expected     3.85068
_refine_ls_R_I_factor            3.11534
_refine_ls_matrix_type           sparse
_refine_ls_weighting_scheme      sigma
_refine_ls_weighting_details     ?
_refine_ls_hydrogen_treatment    ?
_refine_ls_extinction_method     none
_refine_ls_number_parameters     42
_refine_ls_number_restraints     ?
_refine_ls_number_constraints    ?
_refine_diff_density_max         ?
_refine_diff_density_min         ?
_refine_ls_shift/su_max          <0.01


_pd_proc_info_data_reduction     
;
Data reduction performed using Mantid
;

_refine_special_details          
;
The molecular structure is refined via a rigid body Z-matrix. All 
intramolecular geometry is constrained to the values determined from 
high-resolution powder neutron data (ALOXAN14). These parameters are not
expected to change with pressure.

Refinements show that the sample is only partially deuterated. H and D atoms 
sites were both included in the refinement, where an overall H/D occupancy is 
refined against all data.

Isotropic displacement parameters for C and N atoms are allowed to refine for 
lower-pressure structures. Parameters for the O and D/H atoms were fixed at 
1.5x the value of the parent atoms, due to unstable refinement - these ratios 
are informed by the approximate values obtained when refining against a 
preliminary data collection carried out in a vanadium can (not reported). Above
approximately 3 GPa, no displacement parameters could be stably refined, so 
they were then held fixed to the last stably-refined values.

The number of parameters quoted in the CIFs for each pressure point, includes 9
background terms and 23 parameters corresponding to contaminant phases (WC, Ni 
and Pb) which arise from the sample environment. Alloxan accounts for 10 of the
number of parameters quoted.

Sample pressures are determined using the refined lead lattice parameter and a 
Birch-Murnaghan equation of state.
;

#CHECK-CIF ALERTS



loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_symmetry_multiplicity
_atom_site_adp_type
_atom_site_B_iso_or_equiv
H1 H 0.1635(13) -0.2361(13) -0.1011(5) 0.748(6) 8 Biso 0.4(2)
D1 D 0.1621(13) -0.2217(13) -0.0971(5) 0.252(6) 8 Biso 0.4(2)
N1 N 0.1476(11) -0.0729(11) -0.0558(3) 1 8 Biso 0.25(16)
C1 C -0.0506(10) -0.0506(10) 0.000 1 4 Biso 0.32(11)
C2 C 0.3260(11) 0.0825(11) -0.0616(3) 1 8 Biso 0.32(11)
C3 C 0.2999(10) 0.2999(10) 0.000 1 4 Biso 0.32(11)
O1 O -0.2011(10) -0.2011(10) 0.000 1 4 Biso 0.48(16)
O2 O 0.4948(14) 0.0493(14) -0.1127(6) 1 8 Biso 0.48(16)
O3 O 0.4465(10) 0.4465(10) 0.000 1 4 Biso 0.48(16)


loop_
_geom_bond_atom_site_label_1
_geom_bond_atom_site_label_2
_geom_bond_distance
_geom_bond_site_symmetry_1
_geom_bond_site_symmetry_2
_geom_bond_publ_flag
O(1) C(1) 1.226(8) . . no
O(2) C(2) 1.216(10) . . no
O(3) C(3) 1.194(8) . . no
N(1) C(1) 1.383(7) . . no
N(1) C(2) 1.365(9) . . no
C(2) C(3) 1.520(7) . . no
N(1) H(1) 1.132(9) . . no
N(1) D(1) 1.032(9) . . no


loop_
_geom_angle_atom_site_label_1
_geom_angle_atom_site_label_2
_geom_angle_atom_site_label_3
_geom_angle
_geom_angle_site_symmetry_1
_geom_angle_site_symmetry_2
_geom_angle_site_symmetry_3
_geom_angle_publ_flag
C(1) N(1) C(2) 126.4(5) . . . no
O(1) C(1) N(1) 121.2(5) . . . no
O(1) C(1) N(1) 121.2(5) . . . no
N(1) C(1) N(1) 117.6(5) . . . no
O(2) C(2) N(1) 122.2(6) . . . no
O(2) C(2) C(3) 122.2(6) . . . no
N(1) C(2) C(3) 115.6(5) . . . no
O(3) C(3) C(2) 120.8(5) . . . no
O(3) C(3) C(2) 120.8(5) . . . no
C(2) C(3) C(2) 118.4(5) . . . no
C(1) N(1) H(1) 116.8(7) . . . no
C(1) N(1) D(1) 116.8(7) . . . no
C(2) N(1) H(1) 116.8(6) . . . no
C(2) N(1) D(1) 116.8(7) . . . no


loop_
_geom_torsion_atom_site_label_1
_geom_torsion_atom_site_label_2
_geom_torsion_atom_site_label_3
_geom_torsion_atom_site_label_4
_geom_torsion
_geom_torsion_site_symmetry_1
_geom_torsion_site_symmetry_2
_geom_torsion_site_symmetry_3
_geom_torsion_site_symmetry_4
_geom_torsion_publ_flag
C(2) N(1) C(1) O(1) 180.0(5) . . . . no
C(2) N(1) C(1) N(1) 0.0(7) . . . . no
C(1) N(1) C(2) O(2) 180.0(6) . . . . no
C(1) N(1) C(2) C(3) 0.0(8) . . . . no
O(2) C(2) C(3) O(3) 0.0(8) . . . . no
O(2) C(2) C(3) C(2) 180.0(6) . . . . no
N(1) C(2) C(3) O(3) 180.0(5) . . . . no
N(1) C(2) C(3) C(2) 0.0(6) . . . . no
H(1) N(1) C(1) O(1) 0.0(8) . . . . no
H(1) N(1) C(1) N(1) 180.0(6) . . . . no
H(1) N(1) C(2) O(2) 0.0(10) . . . . no
H(1) N(1) C(2) C(3) 180.0(6) . . . . no
_exptl_crystal_colour            yellow
_symmetry_space_group_name_H-M   P41212
####################################################################### 
# 
# This file contains crystal structure data downloaded from the 
# Cambridge Structural Database (CSD) hosted by the Cambridge 
# Crystallographic Data Centre (CCDC).
# 
# Full information about CCDC data access policies and citation 
# guidelines are available at http://www.ccdc.cam.ac.uk/access/V1 
# 
# Audit and citation data items may have been added by the CCDC. 
# Please retain this information to preserve the provenance of 
# this file and to allow appropriate attribution of the data. 
# 
#######################################################################

data_Alloxan_1p42GPa
_database_code_depnum_ccdc_archive 'CCDC 1994630'
loop_
_audit_author_name
_audit_author_address
'Nicholas Funnell'
;STFC, ISIS Neutron Facility
United Kingdom
;
_audit_update_record             
;
2020-04-03 deposited with the CCDC.	2020-05-01 downloaded from the CCDC.
;
# start Validation Reply Form
_vrf_PLAT699_Alloxan_1p42GPa     
;
PROBLEM: Missing _exptl_crystal_description Value .......     Please Do !
RESPONSE: Not applicable - powder sample.
;
_vrf_PLAT430_Alloxan_1p42GPa     
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.70 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT041_Alloxan_1p42GPa     
;
PROBLEM: Calc. and Reported SumFormula    Strings  Differ     Please Check
RESPONSE: This is possibly an erroneous alert? The calculated and reported formulae appear to be the same.
;
_vrf_PLAT340_Alloxan_1p42GPa     
;
PROBLEM: Low Bond Precision on  C-C Bonds ...............      0.008 Ang.
RESPONSE: The structure is refined against high-pressure data which suffer from higher signal-to-noise and lower peak resolution that standard powder patterns. Direct refinement of the atomic coordinates is not possible and so the molecular geometry is constrained via a rigid body. This has all led to the low bond precision seen here.
;

_chemical_name_systematic        pyrimidine-2,4,5,6-tetraone
_chemical_name_common            alloxan
_chemical_formula_moiety         'C4 O4 N2 H1.50 D0.50'
_chemical_formula_structural     'C4 O4 N2 H1.50 D0.50'
_chemical_formula_sum            'C4 O4 N2 H1.50 D0.50'
_chemical_formula_weight         142.58
_chemical_compound_source        Sigma-Aldrich

_space_group_crystal_system      Tetragonal
_symmetry_space_group_name_Hall  'P 4abw 2nw'
_space_group_name_H-M            P41212
_symmetry_Int_Tables_number      92

loop_
_symmetry_equiv_pos_as_xyz
'x, y, z '
'-x+1/2, y+1/2, -z+1/4 '
'-y, -x, -z+1/2 '
'-y+1/2, x+1/2, z+1/4 '
'y, x, -z '
'y+1/2, -x+1/2, z-1/4 '
'-x, -y, z+1/2 '
'x+1/2, -y+1/2, -z-1/4 '

_cell_length_a                   5.7382(7)
_cell_length_b                   5.7382(7)
_cell_length_c                   13.747(2)
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_volume                     452.63(13)
_cell_formula_units_Z            4

_cell_measurement_temperature    293.00000
_cell_measurement_pressure       1.42380 #GPa

_cell_special_details            
;
Cell parameters included in refinement
;

_exptl_crystal_density_diffrn    2.092

_pd_spec_mounting                'TiZr Capsule'
_pd_spec_mount_mode              transmission
_pd_char_colour                  yellow
_chemical_absolute_configuration .

_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details   
;
Calculated using MANTID routines.
;

_pd_instr_location               
'ISIS Neutron Facility. Rutherford Appleton Laboratory'
_diffrn_ambient_temperature      293.00000
_diffrn_source                   'Pulsed neutron source'
_diffrn_source_target            W
_diffrn_radiation_type           Neutron
_diffrn_measurement_device_type  'PEARL diffractometer'
_diffrn_radiation_monochromator  none
_diffrn_detector                 'ZnS scintillator'
_diffrn_detector_type            custom

_pd_meas_scan_method             Time-of-flight
_pd_meas_special_details         
;
Time of flight method using a pulsed neutron source
;

# The following three items are used for time-of-flight measurements only.
_pd_instr_dist_src/spec          12800
_pd_instr_dist_spec/detc         800
_pd_meas_2theta_fixed            90

_pr_proc_ls_profile_function     
;
Voigt function convoluted with a back-to-back double exponential.
;

_pd_proc_ls_background_function  'Chebychev polynomial'

_pd_proc_ls_pref_orient_corr     
;
No requirement for preferred orientation correction
;

_refine_ls_goodness_of_fit_all   0.81428
_pd_proc_ls_prof_R_factor        3.16019
_pd_proc_ls_prof_wR_factor       3.16302
_pd_proc_ls_prof_wR_expected     3.88442
_refine_ls_R_I_factor            2.14265
_refine_ls_matrix_type           sparse
_refine_ls_weighting_scheme      sigma
_refine_ls_weighting_details     ?
_refine_ls_hydrogen_treatment    ?
_refine_ls_extinction_method     none
_refine_ls_number_parameters     42
_refine_ls_number_restraints     ?
_refine_ls_number_constraints    ?
_refine_diff_density_max         ?
_refine_diff_density_min         ?
_refine_ls_shift/su_max          <0.01


_pd_proc_info_data_reduction     
;
Data reduction performed using Mantid
;

_refine_special_details          
;
The molecular structure is refined via a rigid body Z-matrix. All 
intramolecular geometry is constrained to the values determined from 
high-resolution powder neutron data (ALOXAN14). These parameters are not
expected to change with pressure.

Refinements show that the sample is only partially deuterated. H and D atoms 
sites were both included in the refinement, where an overall H/D occupancy is 
refined against all data.

Isotropic displacement parameters for C and N atoms are allowed to refine for 
lower-pressure structures. Parameters for the O and D/H atoms were fixed at 
1.5x the value of the parent atoms, due to unstable refinement - these ratios 
are informed by the approximate values obtained when refining against a 
preliminary data collection carried out in a vanadium can (not reported). Above
approximately 3 GPa, no displacement parameters could be stably refined, so 
they were then held fixed to the last stably-refined values.

The number of parameters quoted in the CIFs for each pressure point, includes 9
background terms and 23 parameters corresponding to contaminant phases (WC, Ni 
and Pb) which arise from the sample environment. Alloxan accounts for 10 of the
number of parameters quoted.

Sample pressures are determined using the refined lead lattice parameter and a 
Birch-Murnaghan equation of state.
;

#CHECK-CIF ALERTS


loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_symmetry_multiplicity
_atom_site_adp_type
_atom_site_B_iso_or_equiv
H1 H 0.1652(13) -0.2409(13) -0.0997(6) 0.748(6) 8 Biso 0.7(3)
D1 D 0.1637(13) -0.2263(13) -0.0957(5) 0.252(6) 8 Biso 0.7(3)
N1 N 0.1481(12) -0.0759(12) -0.0550(3) 1 8 Biso 0.48(19)
C1 C -0.0522(11) -0.0522(11) 0.000 1 4 Biso 0.24(10)
C2 C 0.3273(12) 0.0798(12) -0.0607(3) 1 8 Biso 0.24(10)
C3 C 0.2995(11) 0.2995(11) 0.000 1 4 Biso 0.24(10)
O1 O -0.2032(11) -0.2032(11) 0.000 1 4 Biso 0.37(15)
O2 O 0.4980(14) 0.0452(14) -0.1111(6) 1 8 Biso 0.37(15)
O3 O 0.4467(11) 0.4467(11) 0.000 1 4 Biso 0.37(15)


loop_
_geom_bond_atom_site_label_1
_geom_bond_atom_site_label_2
_geom_bond_distance
_geom_bond_site_symmetry_1
_geom_bond_site_symmetry_2
_geom_bond_publ_flag
O(1) C(1) 1.225(9) . . no
O(2) C(2) 1.216(10) . . no
O(3) C(3) 1.195(9) . . no
N(1) C(1) 1.383(8) . . no
N(1) C(2) 1.365(10) . . no
C(2) C(3) 1.520(8) . . no
N(1) H(1) 1.133(10) . . no
N(1) D(1) 1.032(10) . . no



loop_
_geom_angle_atom_site_label_1
_geom_angle_atom_site_label_2
_geom_angle_atom_site_label_3
_geom_angle
_geom_angle_site_symmetry_1
_geom_angle_site_symmetry_2
_geom_angle_site_symmetry_3
_geom_angle_publ_flag
C(1) N(1) C(2) 126.4(6) . . . no
O(1) C(1) N(1) 121.2(5) . . . no
O(1) C(1) N(1) 121.2(5) . . . no
N(1) C(1) N(1) 117.6(6) . . . no
O(2) C(2) N(1) 122.2(7) . . . no
O(2) C(2) C(3) 122.2(7) . . . no
N(1) C(2) C(3) 115.6(5) . . . no
O(3) C(3) C(2) 120.8(5) . . . no
O(3) C(3) C(2) 120.8(5) . . . no
C(2) C(3) C(2) 118.4(5) . . . no
C(1) N(1) H(1) 116.8(7) . . . no
C(1) N(1) D(1) 116.8(7) . . . no
C(2) N(1) H(1) 116.8(7) . . . no
C(2) N(1) D(1) 116.8(7) . . . no


loop_
_geom_torsion_atom_site_label_1
_geom_torsion_atom_site_label_2
_geom_torsion_atom_site_label_3
_geom_torsion_atom_site_label_4
_geom_torsion
_geom_torsion_site_symmetry_1
_geom_torsion_site_symmetry_2
_geom_torsion_site_symmetry_3
_geom_torsion_site_symmetry_4
_geom_torsion_publ_flag
C(2) N(1) C(1) O(1) 180.0(5) . . . . no
C(2) N(1) C(1) N(1) 0.1(8) . . . . no
C(1) N(1) C(2) O(2) 180.0(7) . . . . no
C(1) N(1) C(2) C(3) 0.1(8) . . . . no
O(2) C(2) C(3) O(3) 0.0(9) . . . . no
O(2) C(2) C(3) C(2) 180.0(6) . . . . no
N(1) C(2) C(3) O(3) 180.0(5) . . . . no
N(1) C(2) C(3) C(2) 0.0(7) . . . . no
H(1) N(1) C(1) O(1) 0.0(9) . . . . no
H(1) N(1) C(1) N(1) 180.0(6) . . . . no
H(1) N(1) C(2) O(2) 0.0(10) . . . . no
H(1) N(1) C(2) C(3) 180.0(6) . . . . no
_exptl_crystal_colour            yellow
_symmetry_space_group_name_H-M   P41212
####################################################################### 
# 
# This file contains crystal structure data downloaded from the 
# Cambridge Structural Database (CSD) hosted by the Cambridge 
# Crystallographic Data Centre (CCDC).
# 
# Full information about CCDC data access policies and citation 
# guidelines are available at http://www.ccdc.cam.ac.uk/access/V1 
# 
# Audit and citation data items may have been added by the CCDC. 
# Please retain this information to preserve the provenance of 
# this file and to allow appropriate attribution of the data. 
# 
#######################################################################

data_Alloxan_6p49GPa
_database_code_depnum_ccdc_archive 'CCDC 1994636'
loop_
_audit_author_name
_audit_author_address
'Nicholas Funnell'
;STFC, ISIS Neutron Facility
United Kingdom
;
_audit_update_record             
;
2020-04-03 deposited with the CCDC.	2020-05-01 downloaded from the CCDC.
;
# start Validation Reply Form
_vrf_PLAT699_Alloxan_6p49GPa     
;
PROBLEM: Missing _exptl_crystal_description Value .......     Please Do !
RESPONSE: Not applicable - powder sample.
;
_vrf_PLAT430_Alloxan_6p49GPa     
;
PROBLEM: Short Inter D...A Contact  O1       ..O3       .       2.55 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT430_Alloxan_6p49GPa_2   
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.62 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT430_Alloxan_6p49GPa_3   
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.62 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT041_Alloxan_6p49GPa     
;
PROBLEM: Calc. and Reported SumFormula    Strings  Differ     Please Check
RESPONSE: This is possibly an erroneous alert? The calculated and reported formulae appear to be the same.
;
_vrf_PLAT340_Alloxan_6p49GPa     
;
PROBLEM: Low Bond Precision on  C-C Bonds ...............      0.008 Ang.
RESPONSE: The structure is refined against high-pressure data which suffer from higher signal-to-noise and lower peak resolution that standard powder patterns. Direct refinement of the atomic coordinates is not possible and so the molecular geometry is constrained via a rigid body. This has all led to the low bond precision seen here.
;
_vrf_PLAT430_Alloxan_6p49GPa_4   
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.90 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT430_Alloxan_6p49GPa_5   
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.90 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;

_chemical_name_systematic        pyrimidine-2,4,5,6-tetraone
_chemical_name_common            alloxan
_chemical_formula_moiety         'C4 O4 N2 H1.50 D0.50'
_chemical_formula_structural     'C4 O4 N2 H1.50 D0.50'
_chemical_formula_sum            'C4 O4 N2 H1.50 D0.50'
_chemical_formula_weight         142.58
_chemical_compound_source        Sigma-Aldrich

_space_group_crystal_system      Tetragonal
_symmetry_space_group_name_Hall  'P 4abw 2nw'
_space_group_name_H-M            P41212
_symmetry_Int_Tables_number      92

loop_
_symmetry_equiv_pos_as_xyz
'x, y, z '
'-x+1/2, y+1/2, -z+1/4 '
'-y, -x, -z+1/2 '
'-y+1/2, x+1/2, z+1/4 '
'y, x, -z '
'y+1/2, -x+1/2, z-1/4 '
'-x, -y, z+1/2 '
'x+1/2, -y+1/2, -z-1/4 '

_cell_length_a                   5.5308(15)
_cell_length_b                   5.5308(15)
_cell_length_c                   13.126(4)
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_volume                     401.5(2)
_cell_formula_units_Z            4

_cell_measurement_temperature    293.00000
_cell_measurement_pressure       6.47717 #GPa

_cell_special_details            
;
Cell parameters included in refinement
;

_exptl_crystal_density_diffrn    2.359

_pd_spec_mounting                'TiZr Capsule'
_pd_spec_mount_mode              transmission
_pd_char_colour                  yellow
_chemical_absolute_configuration .

_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details   
;
Calculated using MANTID routines.
;

_pd_instr_location               
'ISIS Neutron Facility. Rutherford Appleton Laboratory'
_diffrn_ambient_temperature      293.00000
_diffrn_source                   'Pulsed neutron source'
_diffrn_source_target            W
_diffrn_radiation_type           Neutron
_diffrn_measurement_device_type  'PEARL diffractometer'
_diffrn_radiation_monochromator  none
_diffrn_detector                 'ZnS scintillator'
_diffrn_detector_type            custom

_pd_meas_scan_method             Time-of-flight
_pd_meas_special_details         
;
Time of flight method using a pulsed neutron source
;

# The following three items are used for time-of-flight measurements only.
_pd_instr_dist_src/spec          12800
_pd_instr_dist_spec/detc         800
_pd_meas_2theta_fixed            90

_pr_proc_ls_profile_function     
;
Voigt function convoluted with a back-to-back double exponential.
;

_pd_proc_ls_background_function  'Chebychev polynomial'

_pd_proc_ls_pref_orient_corr     
;
No requirement for preferred orientation correction
;

_refine_ls_goodness_of_fit_all   1.04323
_pd_proc_ls_prof_R_factor        2.49762
_pd_proc_ls_prof_wR_factor       2.59933
_pd_proc_ls_prof_wR_expected     2.49162
_refine_ls_R_I_factor            1.88669
_refine_ls_matrix_type           sparse
_refine_ls_weighting_scheme      sigma
_refine_ls_weighting_details     ?
_refine_ls_hydrogen_treatment    ?
_refine_ls_extinction_method     none
_refine_ls_number_parameters     40
_refine_ls_number_restraints     ?
_refine_ls_number_constraints    ?
_refine_diff_density_max         ?
_refine_diff_density_min         ?
_refine_ls_shift/su_max          <0.01


_pd_proc_info_data_reduction     
;
Data reduction performed using Mantid
;

_refine_special_details          
;
The molecular structure is refined via a rigid body Z-matrix. All 
intramolecular geometry is constrained to the values determined from 
high-resolution powder neutron data (ALOXAN14). These parameters are not
expected to change with pressure.

Refinements show that the sample is only partially deuterated. H and D atoms 
sites were both included in the refinement, where an overall H/D occupancy is 
refined against all data.

Isotropic displacement parameters for C and N atoms are allowed to refine for 
lower-pressure structures. Parameters for the O and D/H atoms were fixed at 
1.5x the value of the parent atoms, due to unstable refinement - these ratios 
are informed by the approximate values obtained when refining against a 
preliminary data collection carried out in a vanadium can (not reported). Above
approximately 3 GPa, no displacement parameters could be stably refined, so 
they were then held fixed to the last stably-refined values.

The number of parameters quoted in the CIFs for each pressure point, includes 9
background terms and 23 parameters corresponding to contaminant phases (WC, Ni 
and Pb) which arise from the sample environment. Alloxan accounts for 8 of the
number of parameters quoted.

Sample pressures are determined using the refined lead lattice parameter and a 
Birch-Murnaghan equation of state.
;


#CHECK-CIF ALERTS



loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_symmetry_multiplicity
_atom_site_adp_type
_atom_site_B_iso_or_equiv
H1 H 0.1768(14) -0.2375(14) -0.1069(6) 0.748(6) 8 Biso 0.36426
D1 D 0.1753(14) -0.2225(14) -0.1026(6) 0.252(6) 8 Biso 0.36426
N1 N 0.1606(12) -0.0680(12) -0.0590(3) 1 8 Biso 0.24284
C1 C -0.0452(11) -0.0452(11) 0.000 1 4 Biso 0.32639
C2 C 0.3463(12) 0.0939(12) -0.0651(4) 1 8 Biso 0.32639
C3 C 0.3196(11) 0.3196(11) 0.000 1 4 Biso 0.32639
O1 O -0.2020(11) -0.2020(11) 0.000 1 4 Biso 0.489585
O2 O 0.5216(15) 0.0597(15) -0.1191(7) 1 8 Biso 0.489585
O3 O 0.4723(11) 0.4723(11) 0.000 1 4 Biso 0.489585


loop_
_geom_bond_atom_site_label_1
_geom_bond_atom_site_label_2
_geom_bond_distance
_geom_bond_site_symmetry_1
_geom_bond_site_symmetry_2
_geom_bond_publ_flag
O(1) C(1) 1.226(9) . . no
O(2) C(2) 1.216(11) . . no
O(3) C(3) 1.194(9) . . no
N(1) C(1) 1.383(8) . . no
N(1) C(2) 1.365(9) . . no
C(2) C(3) 1.520(8) . . no
N(1) H(1) 1.132(10) . . no
N(1) D(1) 1.032(10) . . no


loop_
_geom_angle_atom_site_label_1
_geom_angle_atom_site_label_2
_geom_angle_atom_site_label_3
_geom_angle
_geom_angle_site_symmetry_1
_geom_angle_site_symmetry_2
_geom_angle_site_symmetry_3
_geom_angle_publ_flag
C(1) N(1) C(2) 126.3(6) . . . no
O(1) C(1) N(1) 121.2(5) . . . no
O(1) C(1) N(1) 121.2(5) . . . no
N(1) C(1) N(1) 117.7(6) . . . no
O(2) C(2) N(1) 122.2(7) . . . no
O(2) C(2) C(3) 122.2(7) . . . no
N(1) C(2) C(3) 115.6(5) . . . no
O(3) C(3) C(2) 120.8(5) . . . no
O(3) C(3) C(2) 120.8(5) . . . no
C(2) C(3) C(2) 118.4(5) . . . no
C(1) N(1) H(1) 116.9(7) . . . no
C(1) N(1) D(1) 116.8(7) . . . no
C(2) N(1) H(1) 116.8(7) . . . no
C(2) N(1) D(1) 116.8(7) . . . no


loop_
_geom_torsion_atom_site_label_1
_geom_torsion_atom_site_label_2
_geom_torsion_atom_site_label_3
_geom_torsion_atom_site_label_4
_geom_torsion
_geom_torsion_site_symmetry_1
_geom_torsion_site_symmetry_2
_geom_torsion_site_symmetry_3
_geom_torsion_site_symmetry_4
_geom_torsion_publ_flag
C(2) N(1) C(1) O(1) 180.0(5) . . . . no
C(2) N(1) C(1) N(1) 0.0(8) . . . . no
C(1) N(1) C(2) O(2) 180.0(7) . . . . no
C(1) N(1) C(2) C(3) 0.0(8) . . . . no
O(2) C(2) C(3) O(3) 0.0(9) . . . . no
O(2) C(2) C(3) C(2) 180.0(7) . . . . no
N(1) C(2) C(3) O(3) 180.0(5) . . . . no
N(1) C(2) C(3) C(2) 0.0(7) . . . . no
H(1) N(1) C(1) O(1) 0.0(8) . . . . no
H(1) N(1) C(1) N(1) 180.0(6) . . . . no
H(1) N(1) C(2) O(2) 0.0(11) . . . . no
H(1) N(1) C(2) C(3) 180.0(6) . . . . no

#===END
_exptl_crystal_colour            yellow
_symmetry_space_group_name_H-M   P41212
####################################################################### 
# 
# This file contains crystal structure data downloaded from the 
# Cambridge Structural Database (CSD) hosted by the Cambridge 
# Crystallographic Data Centre (CCDC).
# 
# Full information about CCDC data access policies and citation 
# guidelines are available at http://www.ccdc.cam.ac.uk/access/V1 
# 
# Audit and citation data items may have been added by the CCDC. 
# Please retain this information to preserve the provenance of 
# this file and to allow appropriate attribution of the data. 
# 
#######################################################################

data_Alloxan_5p24GPa
_database_code_depnum_ccdc_archive 'CCDC 1994635'
loop_
_audit_author_name
_audit_author_address
'Nicholas Funnell'
;STFC, ISIS Neutron Facility
United Kingdom
;
_audit_update_record             
;
2020-04-03 deposited with the CCDC.	2020-05-01 downloaded from the CCDC.
;
# start Validation Reply Form
_vrf_PLAT699_Alloxan_5p24GPa     
;
PROBLEM: Missing _exptl_crystal_description Value .......     Please Do !
RESPONSE: Not applicable - powder sample.
;
_vrf_PLAT430_Alloxan_5p24GPa     
;
PROBLEM: Short Inter D...A Contact  O1       ..O3       .       2.59 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT430_Alloxan_5p24GPa_2   
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.62 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT430_Alloxan_5p24GPa_3   
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.62 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT041_Alloxan_5p24GPa     
;
PROBLEM: Calc. and Reported SumFormula    Strings  Differ     Please Check
RESPONSE: This is possibly an erroneous alert? The calculated and reported formulae appear to be the same.
;
_vrf_PLAT340_Alloxan_5p24GPa     
;
PROBLEM: Low Bond Precision on  C-C Bonds ...............      0.008 Ang.
RESPONSE: The structure is refined against high-pressure data which suffer from higher signal-to-noise and lower peak resolution that standard powder patterns. Direct refinement of the atomic coordinates is not possible and so the molecular geometry is constrained via a rigid body. This has all led to the low bond precision seen here.
;
_vrf_PLAT430_Alloxan_5p24GPa_4   
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.89 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;
_vrf_PLAT430_Alloxan_5p24GPa_5   
;
PROBLEM: Short Inter D...A Contact  O1       ..O2       .       2.89 Ang.
RESPONSE: The crystal structure is experiencing high hydrostatic pressure. Short intermolecular contacts are to be expected.
;

_chemical_name_systematic        pyrimidine-2,4,5,6-tetraone
_chemical_name_common            alloxan
_chemical_formula_moiety         'C4 O4 N2 H1.50 D0.50'
_chemical_formula_structural     'C4 O4 N2 H1.50 D0.50'
_chemical_formula_sum            'C4 O4 N2 H1.50 D0.50'
_chemical_formula_weight         142.58
_chemical_compound_source        Sigma-Aldrich

_space_group_crystal_system      Tetragonal
_symmetry_space_group_name_Hall  'P 4abw 2nw'
_space_group_name_H-M            P41212
_symmetry_Int_Tables_number      92

loop_
_symmetry_equiv_pos_as_xyz
'x, y, z '
'-x+1/2, y+1/2, -z+1/4 '
'-y, -x, -z+1/2 '
'-y+1/2, x+1/2, z+1/4 '
'y, x, -z '
'y+1/2, -x+1/2, z-1/4 '
'-x, -y, z+1/2 '
'x+1/2, -y+1/2, -z-1/4 '

_cell_length_a                   5.5604(12)
_cell_length_b                   5.5604(12)
_cell_length_c                   13.245(4)
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_volume                     409.5(2)
_cell_formula_units_Z            4

_cell_measurement_temperature    293.00000
_cell_measurement_pressure       5.23993 #GPa

_cell_special_details            
;
Cell parameters included in refinement
;

_exptl_crystal_density_diffrn    2.312

_pd_spec_mounting                'TiZr Capsule'
_pd_spec_mount_mode              transmission
_pd_char_colour                  yellow
_chemical_absolute_configuration .

_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details   
;
Calculated using MANTID routines.
;

_pd_instr_location               
'ISIS Neutron Facility. Rutherford Appleton Laboratory'
_diffrn_ambient_temperature      293.00000
_diffrn_source                   'Pulsed neutron source'
_diffrn_source_target            W
_diffrn_radiation_type           Neutron
_diffrn_measurement_device_type  'PEARL diffractometer'
_diffrn_radiation_monochromator  none
_diffrn_detector                 'ZnS scintillator'
_diffrn_detector_type            custom

_pd_meas_scan_method             Time-of-flight
_pd_meas_special_details         
;
Time of flight method using a pulsed neutron source
;

# The following three items are used for time-of-flight measurements only.
_pd_instr_dist_src/spec          12800
_pd_instr_dist_spec/detc         800
_pd_meas_2theta_fixed            90

_pr_proc_ls_profile_function     
;
Voigt function convoluted with a back-to-back double exponential.
;

_pd_proc_ls_background_function  'Chebychev polynomial'

_pd_proc_ls_pref_orient_corr     
;
No requirement for preferred orientation correction
;

_refine_ls_goodness_of_fit_all   1.01741
_pd_proc_ls_prof_R_factor        2.41274
_pd_proc_ls_prof_wR_factor       2.49403
_pd_proc_ls_prof_wR_expected     2.45134
_refine_ls_R_I_factor            1.82540
_refine_ls_matrix_type           sparse
_refine_ls_weighting_scheme      sigma
_refine_ls_weighting_details     ?
_refine_ls_hydrogen_treatment    ?
_refine_ls_extinction_method     none
_refine_ls_number_parameters     40
_refine_ls_number_restraints     ?
_refine_ls_number_constraints    ?
_refine_diff_density_max         ?
_refine_diff_density_min         ?
_refine_ls_shift/su_max          <0.01


_pd_proc_info_data_reduction     
;
Data reduction performed using Mantid
;

_refine_special_details          
;
The molecular structure is refined via a rigid body Z-matrix. All 
intramolecular geometry is constrained to the values determined from 
high-resolution powder neutron data (ALOXAN14). These parameters are not
expected to change with pressure.

Refinements show that the sample is only partially deuterated. H and D atoms 
sites were both included in the refinement, where an overall H/D occupancy is 
refined against all data.

Isotropic displacement parameters for C and N atoms are allowed to refine for 
lower-pressure structures. Parameters for the O and D/H atoms were fixed at 
1.5x the value of the parent atoms, due to unstable refinement - these ratios 
are informed by the approximate values obtained when refining against a 
preliminary data collection carried out in a vanadium can (not reported). Above
approximately 3 GPa, no displacement parameters could be stably refined, so 
they were then held fixed to the last stably-refined values.

The number of parameters quoted in the CIFs for each pressure point, includes 9
background terms and 23 parameters corresponding to contaminant phases (WC, Ni 
and Pb) which arise from the sample environment. Alloxan accounts for 8 of the
number of parameters quoted.

Sample pressures are determined using the refined lead lattice parameter and a 
Birch-Murnaghan equation of state.
;


#CHECK-CIF ALERTS


loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_symmetry_multiplicity
_atom_site_adp_type
_atom_site_B_iso_or_equiv
H1 H 0.1723(13) -0.2427(13) -0.1049(5) 0.748(6) 8 Biso 0.36426
D1 D 0.1708(13) -0.2277(13) -0.1008(5) 0.252(6) 8 Biso 0.36426
N1 N 0.1556(11) -0.0734(11) -0.0579(3) 1 8 Biso 0.24284
C1 C -0.0500(11) -0.0500(11) 0.000 1 4 Biso 0.32639
C2 C 0.3403(12) 0.0875(12) -0.0639(3) 1 8 Biso 0.32639
C3 C 0.3130(11) 0.3130(11) 0.000 1 4 Biso 0.32639
O1 O -0.2059(11) -0.2059(11) 0.000 1 4 Biso 0.489585
O2 O 0.5154(14) 0.0528(14) -0.1170(6) 1 8 Biso 0.489585
O3 O 0.4648(11) 0.4648(11) 0.000 1 4 Biso 0.489585


loop_
_geom_bond_atom_site_label_1
_geom_bond_atom_site_label_2
_geom_bond_distance
_geom_bond_site_symmetry_1
_geom_bond_site_symmetry_2
_geom_bond_publ_flag
O(1) C(1) 1.226(9) . . no
O(2) C(2) 1.217(10) . . no
O(3) C(3) 1.194(9) . . no
N(1) C(1) 1.383(8) . . no
N(1) C(2) 1.364(9) . . no
C(2) C(3) 1.520(8) . . no
N(1) H(1) 1.132(9) . . no
N(1) D(1) 1.033(9) . . no


loop_
_geom_angle_atom_site_label_1
_geom_angle_atom_site_label_2
_geom_angle_atom_site_label_3
_geom_angle
_geom_angle_site_symmetry_1
_geom_angle_site_symmetry_2
_geom_angle_site_symmetry_3
_geom_angle_publ_flag
C(1) N(1) C(2) 126.4(5) . . . no
O(1) C(1) N(1) 121.2(5) . . . no
O(1) C(1) N(1) 121.2(5) . . . no
N(1) C(1) N(1) 117.6(6) . . . no
O(2) C(2) N(1) 122.2(6) . . . no
O(2) C(2) C(3) 122.2(7) . . . no
N(1) C(2) C(3) 115.7(5) . . . no
O(3) C(3) C(2) 120.8(5) . . . no
O(3) C(3) C(2) 120.8(5) . . . no
C(2) C(3) C(2) 118.3(5) . . . no
C(1) N(1) H(1) 116.8(6) . . . no
C(1) N(1) D(1) 116.8(7) . . . no
C(2) N(1) H(1) 116.8(6) . . . no
C(2) N(1) D(1) 116.8(7) . . . no


loop_
_geom_torsion_atom_site_label_1
_geom_torsion_atom_site_label_2
_geom_torsion_atom_site_label_3
_geom_torsion_atom_site_label_4
_geom_torsion
_geom_torsion_site_symmetry_1
_geom_torsion_site_symmetry_2
_geom_torsion_site_symmetry_3
_geom_torsion_site_symmetry_4
_geom_torsion_publ_flag
C(2) N(1) C(1) O(1) 180.0(5) . . . . no
C(2) N(1) C(1) N(1) 0.0(7) . . . . no
C(1) N(1) C(2) O(2) 180.0(6) . . . . no
C(1) N(1) C(2) C(3) 0.0(8) . . . . no
O(2) C(2) C(3) O(3) 0.0(8) . . . . no
O(2) C(2) C(3) C(2) 180.0(6) . . . . no
N(1) C(2) C(3) O(3) 180.0(5) . . . . no
N(1) C(2) C(3) C(2) 0.0(6) . . . . no
H(1) N(1) C(1) O(1) 0.0(8) . . . . no
H(1) N(1) C(1) N(1) 180.0(6) . . . . no
H(1) N(1) C(2) O(2) 0.1(10) . . . . no
H(1) N(1) C(2) C(3) 180.0(6) . . . . no
_exptl_crystal_colour            yellow
_symmetry_space_group_name_H-M   P41212
