# Electronic Supplementary Material (ESI) for Chemical Communications.
# This journal is © The Royal Society of Chemistry 2018

####################################################################### 
# 
# 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. 
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data_CBDA_4A_0m
_database_code_depnum_ccdc_archive 'CCDC 1857653'
_audit_update_record             
;
2018-07-23 deposited with the CCDC.
2018-11-21 downloaded from the CCDC.
;

_audit_creation_method           SHELXL-2014/7
_shelx_SHELXL_version_number     2014/7
_chemical_name_systematic        
'(1R,2S,3R,4S)-rel-3,4-diphenyl-cyclobutane-1,2- dicarboxylic acid'
_chemical_name_common            'CBDA-4 or β-truxinic acid'
_chemical_melting_point          ?
_chemical_formula_moiety         'C18 H16 O4'
_chemical_formula_sum            'C18 H16 O4'
_chemical_formula_weight         296.31

loop_
_atom_type_symbol
_atom_type_description
_atom_type_scat_dispersion_real
_atom_type_scat_dispersion_imag
_atom_type_scat_source
C C 0.0033 0.0016 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
H H 0.0000 0.0000 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'
O O 0.0106 0.0060 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'

_space_group_crystal_system      monoclinic
_space_group_IT_number           14
_space_group_name_H-M_alt        'P 21/c'
_space_group_name_Hall           '-P 2ybc'

_shelx_space_group_comment       
;
The symmetry employed for this shelxl refinement is uniquely defined
by the following loop, which should always be used as a source of
symmetry information in preference to the above space-group names.
They are only intended as comments.
;

loop_
_space_group_symop_operation_xyz
'x, y, z'
'-x, y+1/2, -z+1/2'
'-x, -y, -z'
'x, -y-1/2, z-1/2'

_cell_length_a                   16.2829(11)
_cell_length_b                   5.5494(3)
_cell_length_c                   16.4604(10)
_cell_angle_alpha                90
_cell_angle_beta                 113.418(4)
_cell_angle_gamma                90
_cell_volume                     1364.85(15)
_cell_formula_units_Z            4
_cell_measurement_temperature    100(2)
_cell_measurement_reflns_used    7489
_cell_measurement_theta_min      2.70
_cell_measurement_theta_max      25.19

_exptl_crystal_description       Plate
_exptl_crystal_colour            colourless
_exptl_crystal_density_meas      ?
_exptl_crystal_density_method    ?
_exptl_crystal_density_diffrn    1.442
_exptl_crystal_F_000             624
_exptl_transmission_factor_min   ?
_exptl_transmission_factor_max   ?
_exptl_crystal_size_max          0.600
_exptl_crystal_size_mid          0.450
_exptl_crystal_size_min          0.300
_exptl_absorpt_coefficient_mu    0.102
_shelx_estimated_absorpt_T_min   0.942
_shelx_estimated_absorpt_T_max   0.970
_exptl_absorpt_correction_type   ?
_exptl_absorpt_correction_T_min  ?
_exptl_absorpt_correction_T_max  ?
_exptl_absorpt_process_details   ?
_exptl_absorpt_special_details   ?
_diffrn_ambient_temperature      100(2)
_diffrn_radiation_wavelength     0.71073
_diffrn_radiation_type           MoK\a
_diffrn_source                   ?
_diffrn_measurement_device_type  'Bruker APEX-II CCD'
_diffrn_measurement_method       'φ and ω scans'
_diffrn_detector_area_resol_mean ?
_diffrn_reflns_number            10087
_diffrn_reflns_av_unetI/netI     0.0186
_diffrn_reflns_av_R_equivalents  0.0214
_diffrn_reflns_limit_h_min       -19
_diffrn_reflns_limit_h_max       13
_diffrn_reflns_limit_k_min       -6
_diffrn_reflns_limit_k_max       6
_diffrn_reflns_limit_l_min       -18
_diffrn_reflns_limit_l_max       19
_diffrn_reflns_theta_min         2.492
_diffrn_reflns_theta_max         25.207
_diffrn_reflns_theta_full        25.207
_diffrn_measured_fraction_theta_max 0.994
_diffrn_measured_fraction_theta_full 0.994
_diffrn_reflns_Laue_measured_fraction_max 0.994
_diffrn_reflns_Laue_measured_fraction_full 0.994
_diffrn_reflns_point_group_measured_fraction_max 0.994
_diffrn_reflns_point_group_measured_fraction_full 0.994
_reflns_number_total             2451
_reflns_number_gt                2242
_reflns_threshold_expression     'I > 2σ(I)'
_reflns_Friedel_coverage         0.000
_reflns_Friedel_fraction_max     .
_reflns_Friedel_fraction_full    .

_reflns_special_details          
;
 Reflections were merged by SHELXL according to the crystal
 class for the calculation of statistics and refinement.
 
 _reflns_Friedel_fraction is defined as the number of unique
 Friedel pairs measured divided by the number that would be
 possible theoretically, ignoring centric projections and
 systematic absences.
;

_computing_data_collection       ?
_computing_cell_refinement       ?
_computing_data_reduction        ?
_computing_structure_solution    ?
_computing_structure_refinement  'SHELXL-2014/7 (Sheldrick, 2014)'
_computing_molecular_graphics    ?
_computing_publication_material  ?
_refine_special_details          ?
_refine_ls_structure_factor_coef Fsqd
_refine_ls_matrix_type           full
_refine_ls_weighting_scheme      calc
_refine_ls_weighting_details     
'w=1/[σ²(Fo²)+(0.1000P)²] where P=(Fo²+2Fc²)/3'
_atom_sites_solution_primary     ?
_atom_sites_solution_secondary   ?
_atom_sites_solution_hydrogens   mixed
_refine_ls_hydrogen_treatment    mixed
_refine_ls_extinction_method     none
_refine_ls_extinction_coef       .
_refine_ls_number_reflns         2451
_refine_ls_number_parameters     205
_refine_ls_number_restraints     0
_refine_ls_R_factor_all          0.0362
_refine_ls_R_factor_gt           0.0330
_refine_ls_wR_factor_ref         0.1395
_refine_ls_wR_factor_gt          0.1284
_refine_ls_goodness_of_fit_ref   1.216
_refine_ls_restrained_S_all      1.216
_refine_ls_shift/su_max          0.041
_refine_ls_shift/su_mean         0.005

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_site_symmetry_order
_atom_site_calc_flag
_atom_site_refinement_flags_posn
_atom_site_refinement_flags_adp
_atom_site_refinement_flags_occupancy
_atom_site_disorder_assembly
_atom_site_disorder_group
O1 O 0.41804(6) 0.79748(16) 0.21236(6) 0.0162(3) Uani 1 1 d . . . . .
H13 H 0.4414(11) 0.740(3) 0.1708(12) 0.024 Uiso 1 1 d . U . . .
O2 O 0.35847(6) 0.42675(16) 0.19554(6) 0.0172(3) Uani 1 1 d . . . . .
O3 O 0.49787(6) 1.11761(16) 0.38608(6) 0.0178(3) Uani 1 1 d . . . . .
O4 O 0.54991(6) 0.73989(17) 0.39348(6) 0.0180(3) Uani 1 1 d . . . . .
H14 H 0.5873(12) 0.811(3) 0.3766(11) 0.027 Uiso 1 1 d . U . . .
C1 C 0.16664(8) 0.7988(2) 0.53425(8) 0.0162(3) Uani 1 1 d . . . . .
H1 H 0.1291 0.7646 0.5646 0.019 Uiso 1 1 calc R U . . .
C2 C 0.23234(9) 0.6375(2) 0.53675(9) 0.0169(3) Uani 1 1 d . . . . .
H16 H 0.2399 0.4916 0.5691 0.020 Uiso 1 1 calc R U . . .
C3 C 0.28750(8) 0.6870(2) 0.49226(8) 0.0153(3) Uani 1 1 d . . . . .
H3 H 0.3322 0.5739 0.4945 0.018 Uiso 1 1 calc R U . . .
C4 C 0.27802(8) 0.9000(2) 0.44455(8) 0.0134(3) Uani 1 1 d . . . . .
C5 C 0.33544(8) 0.9687(2) 0.39547(8) 0.0135(3) Uani 1 1 d . . . . .
H6 H 0.3617 1.1332 0.4128 0.016 Uiso 1 1 calc R U . . .
C6 C 0.28987(8) 0.9397(2) 0.29101(8) 0.0130(3) Uani 1 1 d . . . . .
H7 H 0.3182 1.0581 0.2643 0.016 Uiso 1 1 calc R U . . .
C7 C 0.19022(8) 0.9530(2) 0.24051(8) 0.0134(3) Uani 1 1 d . . . . .
C8 C 0.15384(8) 1.1508(2) 0.18556(8) 0.0148(3) Uani 1 1 d . . . . .
H9 H 0.1923 1.2752 0.1818 0.018 Uiso 1 1 calc R U . . .
C9 C 0.06235(9) 1.1685(2) 0.13630(9) 0.0169(3) Uani 1 1 d . . . . .
H10 H 0.0386 1.3049 0.0995 0.020 Uiso 1 1 calc R U . . .
C10 C 0.00552(8) 0.9875(2) 0.14064(9) 0.0174(3) Uani 1 1 d . . . . .
H2 H -0.0570 0.9984 0.1063 0.021 Uiso 1 1 calc R U . . .
C11 C 0.21120(8) 1.0608(2) 0.44259(8) 0.0160(3) Uani 1 1 d . . . . .
H5 H 0.2033 1.2069 0.4103 0.019 Uiso 1 1 calc R U . . .
C12 C 0.15626(9) 1.0117(2) 0.48668(8) 0.0175(3) Uani 1 1 d . . . . .
H4 H 0.1113 1.1239 0.4844 0.021 Uiso 1 1 calc R U . . .
C13 C 0.40697(8) 0.7853(2) 0.39532(8) 0.0143(3) Uani 1 1 d . . . . .
H15 H 0.4211 0.6599 0.4426 0.017 Uiso 1 1 calc R U . . .
C14 C 0.33971(8) 0.6954(2) 0.30162(8) 0.0136(3) Uani 1 1 d . . . . .
H12 H 0.3017 0.5630 0.3093 0.016 Uiso 1 1 calc R U . . .
C15 C 0.13204(9) 0.7738(2) 0.24550(8) 0.0144(3) Uani 1 1 d . . . . .
H8 H 0.1553 0.6394 0.2835 0.017 Uiso 1 1 calc R U . . .
C16 C 0.04049(9) 0.7902(2) 0.19544(8) 0.0159(3) Uani 1 1 d . . . . .
H11 H 0.0018 0.6661 0.1987 0.019 Uiso 1 1 calc R U . . .
C17 C 0.37301(8) 0.6245(2) 0.23151(8) 0.0139(3) Uani 1 1 d . . . . .
C18 C 0.48896(8) 0.9009(2) 0.39139(8) 0.0139(3) Uani 1 1 d . . . . .


_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
O1 C17 1.3198(15) . ?
O1 H13 0.961(18) . ?
O2 C17 1.2247(16) . ?
O3 C18 1.2185(16) . ?
O4 C18 1.3258(16) . ?
O4 H14 0.859(17) . ?
C1 C2 1.3829(18) . ?
C1 C12 1.3900(19) . ?
C1 H1 0.9500 . ?
C2 C3 1.3930(19) . ?
C2 H16 0.9500 . ?
C3 C4 1.3938(19) . ?
C3 H3 0.9500 . ?
C4 C11 1.3973(18) . ?
C4 C5 1.5074(18) . ?
C5 C13 1.5478(17) . ?
C5 C6 1.5870(17) . ?
C5 H6 1.0000 . ?
C6 C7 1.5023(17) . ?
C6 C14 1.5540(17) . ?
C6 H7 1.0000 . ?
C7 C8 1.3957(18) . ?
C7 C15 1.3981(18) . ?
C8 C9 1.3879(18) . ?
C8 H9 0.9500 . ?
C9 C10 1.3867(19) . ?
C9 H10 0.9500 . ?
C10 C16 1.3887(18) . ?
C10 H2 0.9500 . ?
C11 C12 1.3845(19) . ?
C11 H5 0.9500 . ?
C12 H4 0.9500 . ?
C13 C18 1.5057(18) . ?
C13 C14 1.5762(17) . ?
C13 H15 1.0000 . ?
C14 C17 1.5092(18) . ?
C14 H12 1.0000 . ?
C15 C16 1.3903(18) . ?
C15 H8 0.9500 . ?
C16 H11 0.9500 . ?

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
C17 O1 H13 110.1(9) . . ?
C18 O4 H14 107.6(11) . . ?
C2 C1 C12 119.09(12) . . ?
C2 C1 H1 120.5 . . ?
C12 C1 H1 120.5 . . ?
C1 C2 C3 120.64(12) . . ?
C1 C2 H16 119.7 . . ?
C3 C2 H16 119.7 . . ?
C2 C3 C4 120.87(12) . . ?
C2 C3 H3 119.6 . . ?
C4 C3 H3 119.6 . . ?
C3 C4 C11 117.73(12) . . ?
C3 C4 C5 124.28(11) . . ?
C11 C4 C5 117.99(11) . . ?
C4 C5 C13 117.51(10) . . ?
C4 C5 C6 115.62(10) . . ?
C13 C5 C6 87.69(9) . . ?
C4 C5 H6 111.3 . . ?
C13 C5 H6 111.3 . . ?
C6 C5 H6 111.3 . . ?
C7 C6 C14 120.40(10) . . ?
C7 C6 C5 122.11(10) . . ?
C14 C6 C5 88.19(9) . . ?
C7 C6 H7 108.1 . . ?
C14 C6 H7 108.1 . . ?
C5 C6 H7 108.1 . . ?
C8 C7 C15 118.32(11) . . ?
C8 C7 C6 118.95(11) . . ?
C15 C7 C6 122.72(11) . . ?
C9 C8 C7 120.99(12) . . ?
C9 C8 H9 119.5 . . ?
C7 C8 H9 119.5 . . ?
C10 C9 C8 120.13(12) . . ?
C10 C9 H10 119.9 . . ?
C8 C9 H10 119.9 . . ?
C9 C10 C16 119.66(11) . . ?
C9 C10 H2 120.2 . . ?
C16 C10 H2 120.2 . . ?
C12 C11 C4 121.45(12) . . ?
C12 C11 H5 119.3 . . ?
C4 C11 H5 119.3 . . ?
C11 C12 C1 120.21(12) . . ?
C11 C12 H4 119.9 . . ?
C1 C12 H4 119.9 . . ?
C18 C13 C5 113.60(10) . . ?
C18 C13 C14 112.08(10) . . ?
C5 C13 C14 88.80(9) . . ?
C18 C13 H15 113.4 . . ?
C5 C13 H15 113.4 . . ?
C14 C13 H15 113.4 . . ?
C17 C14 C6 118.15(10) . . ?
C17 C14 C13 120.64(10) . . ?
C6 C14 C13 87.86(9) . . ?
C17 C14 H12 109.5 . . ?
C6 C14 H12 109.5 . . ?
C13 C14 H12 109.5 . . ?
C16 C15 C7 120.70(11) . . ?
C16 C15 H8 119.7 . . ?
C7 C15 H8 119.7 . . ?
C10 C16 C15 120.19(11) . . ?
C10 C16 H11 119.9 . . ?
C15 C16 H11 119.9 . . ?
O2 C17 O1 123.73(12) . . ?
O2 C17 C14 122.95(11) . . ?
O1 C17 C14 113.32(10) . . ?
O3 C18 O4 123.90(12) . . ?
O3 C18 C13 123.82(12) . . ?
O4 C18 C13 112.27(11) . . ?

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
C12 C1 C2 C3 -0.03(19) . . . . ?
C1 C2 C3 C4 0.24(19) . . . . ?
C2 C3 C4 C11 -0.34(18) . . . . ?
C2 C3 C4 C5 179.29(12) . . . . ?
C3 C4 C5 C13 2.50(17) . . . . ?
C11 C4 C5 C13 -177.86(11) . . . . ?
C3 C4 C5 C6 104.00(14) . . . . ?
C11 C4 C5 C6 -76.36(14) . . . . ?
C4 C5 C6 C7 26.34(16) . . . . ?
C13 C5 C6 C7 145.90(11) . . . . ?
C4 C5 C6 C14 -98.96(11) . . . . ?
C13 C5 C6 C14 20.60(9) . . . . ?
C14 C6 C7 C8 -140.48(12) . . . . ?
C5 C6 C7 C8 110.56(14) . . . . ?
C14 C6 C7 C15 38.89(18) . . . . ?
C5 C6 C7 C15 -70.07(16) . . . . ?
C15 C7 C8 C9 -0.67(19) . . . . ?
C6 C7 C8 C9 178.73(12) . . . . ?
C7 C8 C9 C10 -0.46(19) . . . . ?
C8 C9 C10 C16 0.89(19) . . . . ?
C3 C4 C11 C12 0.26(19) . . . . ?
C5 C4 C11 C12 -179.40(11) . . . . ?
C4 C11 C12 C1 -0.06(19) . . . . ?
C2 C1 C12 C11 -0.06(19) . . . . ?
C4 C5 C13 C18 -148.81(11) . . . . ?
C6 C5 C13 C18 93.36(11) . . . . ?
C4 C5 C13 C14 97.54(11) . . . . ?
C6 C5 C13 C14 -20.29(9) . . . . ?
C7 C6 C14 C17 89.11(14) . . . . ?
C5 C6 C14 C17 -144.16(11) . . . . ?
C7 C6 C14 C13 -146.94(12) . . . . ?
C5 C6 C14 C13 -20.21(9) . . . . ?
C18 C13 C14 C17 27.45(15) . . . . ?
C5 C13 C14 C17 142.51(11) . . . . ?
C18 C13 C14 C6 -94.32(11) . . . . ?
C5 C13 C14 C6 20.74(9) . . . . ?
C8 C7 C15 C16 1.37(18) . . . . ?
C6 C7 C15 C16 -178.00(12) . . . . ?
C9 C10 C16 C15 -0.19(19) . . . . ?
C7 C15 C16 C10 -0.95(19) . . . . ?
C6 C14 C17 O2 -130.36(13) . . . . ?
C13 C14 C17 O2 124.12(13) . . . . ?
C6 C14 C17 O1 48.83(14) . . . . ?
C13 C14 C17 O1 -56.69(14) . . . . ?
C5 C13 C18 O3 -2.13(17) . . . . ?
C14 C13 C18 O3 96.64(14) . . . . ?
C5 C13 C18 O4 178.49(10) . . . . ?
C14 C13 C18 O4 -82.73(12) . . . . ?

_refine_diff_density_max         0.254
_refine_diff_density_min         -0.230
_refine_diff_density_rms         0.040



