# Electronic Supplementary Material (ESI) for ChemComm.
# This journal is © The Royal Society of Chemistry 2014

#######################################################################
#
#                 Cambridge Crystallographic Data Centre
#                                CCDC 
# 
#######################################################################
# 
#  This CIF contains data from an original supplementary publication
#  deposited with the CCDC, and may include chemical, crystal,
#  experimental, refinement, atomic coordinates,
#  anisotropic displacement parameters and molecular geometry data,
#  as required by the journal to which it was submitted.
#
#  This CIF is provided on the understanding that it is used for bona
#  fide research purposes only. It may contain copyright material
#  of the CCDC or of third parties, and may not be copied or further
#  disseminated in any form, whether machine-readable or not,
#  except for the purpose of generating routine backup copies
#  on your local computer system.
# 
#  For further information on the CCDC, data deposition and
#  data retrieval see:
#                         www.ccdc.cam.ac.uk
#
#  Bona fide researchers may freely download Mercury and enCIFer
#  from this site to visualise CIF-encoded structures and 
#  to carry out CIF format checking respectively.
#
data_tetrah

_audit_creation_date             2014-06-26T15:42:14-00:00
_audit_creation_method           'WinGX routine CIF_UPDATE'
_audit_conform_dict_name         cif_core.dic
_audit_conform_dict_version      2.3
_audit_conform_dict_location     ftp://ftp.iucr.org/pub/cif_core.dic

#----------------------------------------------------------------------------#
#                   CHEMICAL INFORMATION                                     #
#----------------------------------------------------------------------------#

_chemical_name_systematic        
;
 ?
;
_chemical_formula_moiety         'C28 H30 N2 Si2'
_chemical_formula_sum            'C50 H56 N4 Si4'
_chemical_formula_weight         825.37
_chemical_compound_source        'synthesis as described'

#----------------------------------------------------------------------------#
#                   UNIT CELL INFORMATION                                    #
#----------------------------------------------------------------------------#

_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_H-M   'P 1 21/c 1'
_symmetry_space_group_name_Hall  '-P 2ybc'
_symmetry_Int_Tables_number      14
loop_
_symmetry_equiv_pos_as_xyz
'x, y, z'
'-x, y+1/2, -z+1/2'
'-x, -y, -z'
'x, -y-1/2, z-1/2'

_cell_length_a                   13.953(4)
_cell_length_b                   10.739(4)
_cell_length_c                   18.125(8)
_cell_angle_alpha                90
_cell_angle_beta                 105.53(3)
_cell_angle_gamma                90
_cell_volume                     2616.6(17)
_cell_formula_units_Z            2
_cell_measurement_temperature    293(2)
_cell_measurement_reflns_used    20
_cell_measurement_theta_min      30
_cell_measurement_theta_max      35
_cell_measurement_wavelength     1.54176

#----------------------------------------------------------------------------#
#                   CRYSTAL INFORMATION                                      #
#----------------------------------------------------------------------------#

_exptl_crystal_description       prism
_exptl_crystal_colour            red
_exptl_crystal_size_max          0.5
_exptl_crystal_size_mid          0.3
_exptl_crystal_size_min          0.2
_exptl_crystal_density_diffrn    1.048
_exptl_crystal_density_method    'not measured'
_exptl_crystal_F_000             880
_exptl_special_details           
;
 ?
;

#----------------------------------------------------------------------------#
#                   ABSORPTION CORRECTION                                    #
#----------------------------------------------------------------------------#

_exptl_absorpt_coefficient_mu    1.307
_exptl_absorpt_correction_type   Empirical
_exptl_absorpt_process_details   'psi scan'
_exptl_absorpt_correction_T_min  0.7291
_exptl_absorpt_correction_T_max  0.8769

#----------------------------------------------------------------------------#
#                   DATA COLLECTION                                          #
#----------------------------------------------------------------------------#

_diffrn_ambient_temperature      293(2)
_diffrn_radiation_wavelength     1.54176
_diffrn_radiation_type           CuK\a
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_probe          x-ray
_diffrn_reflns_av_R_equivalents  0
_diffrn_reflns_av_unetI/netI     0.052
_diffrn_reflns_number            4885
_diffrn_reflns_limit_h_min       -17
_diffrn_reflns_limit_h_max       16
_diffrn_reflns_limit_k_min       0
_diffrn_reflns_limit_k_max       13
_diffrn_reflns_limit_l_min       0
_diffrn_reflns_limit_l_max       22
_diffrn_reflns_theta_min         3.29
_diffrn_reflns_theta_max         70.02
_diffrn_reflns_theta_full        70
_diffrn_measured_fraction_theta_full 0.986
_diffrn_measured_fraction_theta_max 0.986
_reflns_number_total             4885
_reflns_number_gt                1802
_reflns_threshold_expression     >2sigma(I)

#----------------------------------------------------------------------------#
#                   COMPUTER PROGRAMS USED                                   #
#----------------------------------------------------------------------------#

_computing_structure_solution    'SHELXS-97 (Sheldrick, 1997)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_molecular_graphics    'Ortep-3 for Windows (Farrugia, 1997)'
_computing_publication_material  'WinGX publication routines (Farrugia, 1999)'

#----------------------------------------------------------------------------#
#                   REFINEMENT INFORMATION                                   #
#----------------------------------------------------------------------------#

_refine_special_details          
;
 Refinement of F² against ALL reflections.  The weighted R-factor wR and
 goodness of fit S are based on F², conventional R-factors R are based
 on F, with F set to zero for negative F². The threshold expression of
 F² > 2sigma(F²) is used only for calculating R-factors(gt) etc. and is
 not relevant to the choice of reflections for refinement.  R-factors based
 on F² are statistically about twice as large as those based on F, and R-
 factors based on ALL data will be even larger.
;
_refine_ls_structure_factor_coef Fsqd
_refine_ls_matrix_type           full
_refine_ls_weighting_scheme      calc
_refine_ls_weighting_details     
'calc w=1/[σ²(Fo²)+(0.1993P)²+0.0000P] where P=(Fo²+2Fc²)/3'
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_atom_sites_solution_hydrogens   geom
_refine_ls_hydrogen_treatment    none
_refine_ls_extinction_method     SHELXL
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4^
_refine_ls_extinction_coef       0.0044(10)
_refine_ls_number_reflns         4885
_refine_ls_number_parameters     269
_refine_ls_number_restraints     0
_refine_ls_R_factor_all          0.2092
_refine_ls_R_factor_gt           0.1051
_refine_ls_wR_factor_ref         0.3591
_refine_ls_wR_factor_gt          0.2971
_refine_ls_goodness_of_fit_ref   0.952
_refine_ls_restrained_S_all      0.952
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0
_refine_diff_density_max         0.44
_refine_diff_density_min         -0.276
_refine_diff_density_rms         0.06

#----------------------------------------------------------------------------#
#                   ATOMIC TYPES, COORDINATES AND THERMAL PARAMETERS         #
#----------------------------------------------------------------------------#

loop_
_atom_type_symbol
_atom_type_description
_atom_type_scat_dispersion_real
_atom_type_scat_dispersion_imag
_atom_type_scat_source
C C 0.018 0.009 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
H H 0 0 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
N N 0.031 0.018 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
Si Si 0.254 0.33 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'

loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_U_iso_or_equiv
_atom_site_adp_type
_atom_site_occupancy
_atom_site_symmetry_multiplicity
_atom_site_calc_flag
_atom_site_refinement_flags
_atom_site_disorder_assembly
_atom_site_disorder_group
Si1 Si 0.60899(16) 0.0595(2) 0.19557(12) 0.1431(10) Uani 1 1 d . . .
Si2 Si 0.82140(19) -0.4036(2) 0.38255(13) 0.1472(10) Uani 1 1 d . . .
N2 N 0.8051(4) 0.0677(4) 0.4603(2) 0.0953(13) Uani 1 1 d . . .
N1 N 0.9154(3) 0.1578(4) 0.3789(2) 0.1041(14) Uani 1 1 d . . .
H1 H 0.8517 0.1604 0.3699 0.125 Uiso 1 1 calc R . .
C003 C 0.9648(5) 0.0799(4) 0.4367(3) 0.0897(16) Uani 1 1 d . . .
C004 C 1.0591(4) 0.0485(4) 0.4538(3) 0.0916(15) Uani 1 1 d . . .
H004 H 1.0984 0.0796 0.4239 0.11 Uiso 1 1 calc R . .
C005 C 0.9580(4) 0.2344(5) 0.3324(3) 0.0987(17) Uani 1 1 d . . .
C006 C 0.8980(4) 0.2563(5) 0.2567(3) 0.1007(17) Uani 1 1 d . . .
C007 C 0.8953(5) 0.0331(4) 0.4820(3) 0.0898(16) Uani 1 1 d . . .
C008 C 0.7372(5) 0.0256(6) 0.5001(3) 0.1016(18) Uani 1 1 d . . .
C009 C 1.0466(5) 0.2912(6) 0.3593(3) 0.1118(19) Uani 1 1 d . . .
H009 H 1.084 0.2771 0.4094 0.134 Uiso 1 1 calc R . .
C010 C 0.8053(5) 0.1967(6) 0.2315(3) 0.1069(19) Uani 1 1 d . . .
C011 C 0.7000(6) 0.1101(7) 0.5426(4) 0.122(2) Uani 1 1 d . . .
H011 H 0.7206 0.1926 0.544 0.146 Uiso 1 1 calc R . .
C012 C 0.7384(5) -0.1898(6) 0.4544(3) 0.1092(19) Uani 1 1 d . . .
C013 C 0.9356(6) 0.3376(7) 0.2117(4) 0.126(2) Uani 1 1 d . . .
H013 H 0.8978 0.3543 0.162 0.151 Uiso 1 1 calc R . .
C014 C 0.7026(5) -0.0957(6) 0.4961(3) 0.1034(17) Uani 1 1 d . . .
C015 C 1.0266(7) 0.3939(7) 0.2380(4) 0.137(2) Uani 1 1 d . . .
H015 H 1.0503 0.4467 0.2061 0.164 Uiso 1 1 calc R . .
C016 C 1.0827(5) 0.3719(6) 0.3117(4) 0.128(2) Uani 1 1 d . . .
H016 H 1.1443 0.4103 0.33 0.153 Uiso 1 1 calc R . .
C017 C 0.7286(5) 0.1432(6) 0.2131(3) 0.114(2) Uani 1 1 d . . .
C018 C 0.7690(5) -0.2733(7) 0.4216(4) 0.127(2) Uani 1 1 d . . .
C019 C 0.5979(6) -0.0420(10) 0.5778(4) 0.144(3) Uani 1 1 d . . .
H019 H 0.5512 -0.0653 0.6034 0.173 Uiso 1 1 calc R . .
C020 C 0.6336(7) 0.0767(9) 0.5829(5) 0.144(3) Uani 1 1 d . . .
H020 H 0.6131 0.1348 0.6135 0.172 Uiso 1 1 calc R . .
C021 C 0.6317(6) -0.1252(7) 0.5346(4) 0.128(2) Uani 1 1 d . . .
H021 H 0.6064 -0.2058 0.5305 0.154 Uiso 1 1 calc R . .
C022 C 0.7851(9) -0.5465(8) 0.4264(8) 0.232(5) Uani 1 1 d . . .
H02A H 0.8131 -0.5439 0.4808 0.348 Uiso 1 1 calc R . .
H02B H 0.8096 -0.6185 0.4058 0.348 Uiso 1 1 calc R . .
H02C H 0.7139 -0.5508 0.415 0.348 Uiso 1 1 calc R . .
C023 C 0.9570(7) -0.3841(9) 0.4114(6) 0.189(4) Uani 1 1 d . . .
H02D H 0.974 -0.3049 0.3938 0.283 Uiso 1 1 calc R . .
H02E H 0.9873 -0.4495 0.3894 0.283 Uiso 1 1 calc R . .
H02F H 0.9807 -0.3878 0.4662 0.283 Uiso 1 1 calc R . .
C024 C 0.7767(10) -0.4048(11) 0.2756(5) 0.244(6) Uani 1 1 d . . .
H02G H 0.7055 -0.4116 0.2602 0.366 Uiso 1 1 calc R . .
H02H H 0.8053 -0.4745 0.256 0.366 Uiso 1 1 calc R . .
H02I H 0.7964 -0.3289 0.2557 0.366 Uiso 1 1 calc R . .
C025 C 0.5323(12) 0.0922(19) 0.1081(12) 0.465(19) Uani 1 1 d . . .
H02J H 0.5204 0.0177 0.0777 0.697 Uiso 1 1 calc R . .
H02K H 0.5627 0.1537 0.0833 0.697 Uiso 1 1 calc R . .
H02L H 0.4703 0.1236 0.1138 0.697 Uiso 1 1 calc R . .
C026 C 0.6307(12) -0.0968(13) 0.2108(18) 0.52(2) Uani 1 1 d . . .
H02M H 0.578 -0.1432 0.177 0.78 Uiso 1 1 calc R . .
H02N H 0.6332 -0.1165 0.2629 0.78 Uiso 1 1 calc R . .
H02O H 0.6929 -0.1181 0.2009 0.78 Uiso 1 1 calc R . .
C027 C 0.5563(12) 0.101(3) 0.2670(14) 0.58(3) Uani 1 1 d . . .
H02P H 0.5973 0.0721 0.3152 0.871 Uiso 1 1 calc R . .
H02Q H 0.4914 0.0642 0.2575 0.871 Uiso 1 1 calc R . .
H02R H 0.5506 0.19 0.2682 0.871 Uiso 1 1 calc R . .



#----------------------------------------------------------------------------#
#                   MOLECULAR GEOMETRY                                       #
#----------------------------------------------------------------------------#

_geom_special_details            
;
 All esds (except the esd in the dihedral angle between two l.s. planes)
 are estimated using the full covariance matrix.  The cell esds are taken
 into account individually in the estimation of esds in distances, angles
 and torsion angles; correlations between esds in cell parameters are only
 used when they are defined by crystal symmetry.  An approximate (isotropic)
 treatment of cell esds is used for estimating esds involving l.s. planes.
;
loop_
_geom_bond_atom_site_label_1
_geom_bond_atom_site_label_2
_geom_bond_distance
_geom_bond_site_symmetry_2
_geom_bond_publ_flag
Si1 C025 1.695(15) . ?
Si1 C027 1.710(15) . ?
Si1 C026 1.714(14) . ?
Si1 C017 1.847(8) . ?
Si2 C018 1.808(8) . ?
Si2 C023 1.835(10) . ?
Si2 C022 1.859(10) . ?
Si2 C024 1.871(10) . ?
N2 C007 1.269(6) . ?
N2 C008 1.411(8) . ?
N1 C003 1.374(6) . ?
N1 C005 1.417(7) . ?
C003 C004 1.312(7) . ?
C003 C007 1.516(8) . ?
C004 C007 1.459(7) 3_756 ?
C005 C009 1.348(8) . ?
C005 C006 1.422(7) . ?
C006 C013 1.391(8) . ?
C006 C010 1.405(9) . ?
C007 C004 1.459(7) 3_756 ?
C008 C011 1.379(9) . ?
C008 C014 1.384(9) . ?
C009 C016 1.408(9) . ?
C010 C017 1.182(8) . ?
C011 C020 1.372(10) . ?
C012 C018 1.215(9) . ?
C012 C014 1.428(9) . ?
C013 C015 1.371(9) . ?
C014 C021 1.392(9) . ?
C015 C016 1.376(9) . ?
C019 C021 1.353(10) . ?
C019 C020 1.363(11) . ?

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_3
_geom_angle_publ_flag
C025 Si1 C027 111.2(14) . . ?
C025 Si1 C026 113.2(11) . . ?
C027 Si1 C026 103.1(16) . . ?
C025 Si1 C017 112.0(5) . . ?
C027 Si1 C017 107.1(5) . . ?
C026 Si1 C017 109.7(6) . . ?
C018 Si2 C023 107.1(4) . . ?
C018 Si2 C022 106.6(4) . . ?
C023 Si2 C022 110.5(5) . . ?
C018 Si2 C024 110.7(4) . . ?
C023 Si2 C024 109.2(5) . . ?
C022 Si2 C024 112.5(6) . . ?
C007 N2 C008 119.5(4) . . ?
C003 N1 C005 127.0(5) . . ?
C004 C003 N1 127.1(6) . . ?
C004 C003 C007 122.3(4) . . ?
N1 C003 C007 110.6(5) . . ?
C003 C004 C007 122.6(5) . 3_756 ?
C009 C005 N1 122.5(5) . . ?
C009 C005 C006 121.3(6) . . ?
N1 C005 C006 115.9(5) . . ?
C013 C006 C010 123.6(5) . . ?
C013 C006 C005 117.0(6) . . ?
C010 C006 C005 119.4(6) . . ?
N2 C007 C004 127.5(6) . 3_756 ?
N2 C007 C003 117.4(5) . . ?
C004 C007 C003 115.2(5) 3_756 . ?
C011 C008 C014 118.1(7) . . ?
C011 C008 N2 118.7(7) . . ?
C014 C008 N2 123.2(6) . . ?
C005 C009 C016 120.0(6) . . ?
C017 C010 C006 177.0(6) . . ?
C020 C011 C008 122.3(8) . . ?
C018 C012 C014 177.1(7) . . ?
C015 C013 C006 122.2(6) . . ?
C008 C014 C021 118.2(7) . . ?
C008 C014 C012 121.8(7) . . ?
C021 C014 C012 120.0(7) . . ?
C013 C015 C016 119.7(7) . . ?
C015 C016 C009 119.8(7) . . ?
C010 C017 Si1 173.7(6) . . ?
C012 C018 Si2 174.0(6) . . ?
C021 C019 C020 118.6(9) . . ?
C019 C020 C011 119.7(8) . . ?
C019 C021 C014 123.0(8) . . ?

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
C005 N1 C003 C004 -9.6(8) . . . . ?
C005 N1 C003 C007 169.4(5) . . . . ?
N1 C003 C004 C007 178.5(4) . . . 3_756 ?
C007 C003 C004 C007 -0.3(8) . . . 3_756 ?
C003 N1 C005 C009 -35.4(9) . . . . ?
C003 N1 C005 C006 149.6(5) . . . . ?
C009 C005 C006 C013 0.9(9) . . . . ?
N1 C005 C006 C013 176.0(5) . . . . ?
C009 C005 C006 C010 -178.9(6) . . . . ?
N1 C005 C006 C010 -3.7(8) . . . . ?
C008 N2 C007 C004 -0.1(8) . . . 3_756 ?
C008 N2 C007 C003 179.3(5) . . . . ?
C004 C003 C007 N2 -179.2(5) . . . . ?
N1 C003 C007 N2 1.8(6) . . . . ?
C004 C003 C007 C004 0.3(7) . . . 3_756 ?
N1 C003 C007 C004 -178.7(4) . . . 3_756 ?
C007 N2 C008 C011 110.9(6) . . . . ?
C007 N2 C008 C014 -71.9(6) . . . . ?
N1 C005 C009 C016 -176.4(6) . . . . ?
C006 C005 C009 C016 -1.6(9) . . . . ?
C013 C006 C010 C017 167(14) . . . . ?
C005 C006 C010 C017 -13(14) . . . . ?
C014 C008 C011 C020 2.6(9) . . . . ?
N2 C008 C011 C020 179.9(6) . . . . ?
C010 C006 C013 C015 -179.8(7) . . . . ?
C005 C006 C013 C015 0.5(10) . . . . ?
C011 C008 C014 C021 0.5(8) . . . . ?
N2 C008 C014 C021 -176.7(5) . . . . ?
C011 C008 C014 C012 -178.9(5) . . . . ?
N2 C008 C014 C012 3.9(8) . . . . ?
C018 C012 C014 C008 138(14) . . . . ?
C018 C012 C014 C021 -42(14) . . . . ?
C006 C013 C015 C016 -1.1(11) . . . . ?
C013 C015 C016 C009 0.4(11) . . . . ?
C005 C009 C016 C015 0.9(10) . . . . ?
C006 C010 C017 Si1 40(18) . . . . ?
C025 Si1 C017 C010 150(5) . . . . ?
C027 Si1 C017 C010 28(6) . . . . ?
C026 Si1 C017 C010 -84(6) . . . . ?
C014 C012 C018 Si2 -32(19) . . . . ?
C023 Si2 C018 C012 -62(7) . . . . ?
C022 Si2 C018 C012 56(7) . . . . ?
C024 Si2 C018 C012 18E1(10) . . . . ?
C021 C019 C020 C011 2.1(12) . . . . ?
C008 C011 C020 C019 -4.0(11) . . . . ?
C020 C019 C021 C014 1.1(11) . . . . ?
C008 C014 C021 C019 -2.4(9) . . . . ?
C012 C014 C021 C019 177.1(6) . . . . ?

_database_code_depnum_ccdc_archive 'CCDC 1010886'
