Solid-state chiral resolution mediated by stoichiometry: crystallizing etiracetam with ZnCl<sub>2</sub>.
Shemchuk, Oleksii; Song, Lixing; Robeyns, Koen; Braga, Dario; Grepioni, Fabrizia; Leyssens, Tom; Chemical communications (Cambridge, England) 54 (2018) 10890–10892; doi:10.1039/c8cc06199h

data_7122312
_publ_section_title
;
 Solid-state chiral resolution mediated by stoichiometry: crystallizing
 etiracetam with ZnCl<sub>2</sub>.
;
_journal_issue                   77
_journal_name_full
'Chemical communications (Cambridge, England)'
_journal_page_first              10890
_journal_page_last               10892
_journal_paper_doi               10.1039/c8cc06199h
_journal_volume                  54
_journal_year                    2018
_chemical_absolute_configuration rm
_chemical_formula_moiety         'C16 H28 Cl4 N4 O4 Zn2'
_chemical_formula_sum            'C16 H28 Cl4 N4 O4 Zn2'
_chemical_formula_weight         612.96
_space_group_crystal_system      monoclinic
_space_group_IT_number           4
_space_group_name_Hall           'P 2yb'
_space_group_name_H-M_alt        'P 1 21 1'
_symmetry_space_group_name_Hall  'P 2yb'
_symmetry_space_group_name_H-M   'P 1 21 1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     dual
_audit_creation_date             2018-05-29
_audit_creation_method
;
Olex2 1.2
(compiled 2018.05.18 svn.r3508 for OlexSys, GUI svn.r5497)
;
_audit_update_record
;
2018-07-24 deposited with the CCDC.
2018-09-03 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 98.496(4)
_cell_angle_gamma                90
_cell_formula_units_Z            2
_cell_length_a                   6.3692(3)
_cell_length_b                   11.6771(4)
_cell_length_c                   17.1077(6)
_cell_measurement_reflns_used    1929
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      26.9890
_cell_measurement_theta_min      3.6140
_cell_volume                     1258.40(9)
_computing_cell_refinement       'CrysAlisPro 1.171.38.46 (Rigaku OD, 2015)'
_computing_data_collection       'CrysAlisPro 1.171.38.46 (Rigaku OD, 2015)'
_computing_data_reduction        'CrysAlisPro 1.171.38.46 (Rigaku OD, 2015)'
_computing_molecular_graphics    'Olex2 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 (Dolomanov et al., 2009)'
_computing_structure_refinement  'ShelXL (Sheldrick, 2015)'
_computing_structure_solution    'ShelXT (Sheldrick, 2015)'
_diffrn_ambient_temperature      293(2)
_diffrn_detector                 'CCD plate'
_diffrn_detector_area_resol_mean 16.1340
_diffrn_detector_type            Sapphire3
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.852
_diffrn_measurement_details
;
List of Runs (angles in degrees, time in seconds):

  # Type    Start    End  Width  t~exp~   \w     \q     \k     \f   Frames
  1  \w    -25.00   3.00   1.00    9.21    --  -16.52 -99.00-120.00   28
  2  \w    -38.00  44.00   1.00    9.21    --  -16.52  19.00 -30.00   82
  3  \w    -85.00  21.00   1.00    9.21    --  -16.52 -19.00 120.00  106
;
_diffrn_measurement_device       'four-circle diffractometer'
_diffrn_measurement_device_type  'Xcalibur, Sapphire3'
_diffrn_measurement_method       '\w scans'
_diffrn_orient_matrix_type
'CrysAlisPro convention (1999,Acta A55,543-557)'
_diffrn_orient_matrix_UB_11      -0.0464626000
_diffrn_orient_matrix_UB_12      0.0222871000
_diffrn_orient_matrix_UB_13      0.0320038000
_diffrn_orient_matrix_UB_21      -0.1010683000
_diffrn_orient_matrix_UB_22      -0.0004704000
_diffrn_orient_matrix_UB_23      -0.0238164000
_diffrn_orient_matrix_UB_31      -0.0175306000
_diffrn_orient_matrix_UB_32      -0.0565144000
_diffrn_orient_matrix_UB_33      0.0128382000
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_probe          x-ray
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0240
_diffrn_reflns_av_unetI/netI     0.0595
_diffrn_reflns_Laue_measured_fraction_full 0.998
_diffrn_reflns_Laue_measured_fraction_max 0.852
_diffrn_reflns_limit_h_max       8
_diffrn_reflns_limit_h_min       -8
_diffrn_reflns_limit_k_max       15
_diffrn_reflns_limit_k_min       -11
_diffrn_reflns_limit_l_max       23
_diffrn_reflns_limit_l_min       -17
_diffrn_reflns_number            6011
_diffrn_reflns_point_group_measured_fraction_full 0.843
_diffrn_reflns_point_group_measured_fraction_max 0.682
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         29.109
_diffrn_reflns_theta_min         3.234
_diffrn_source                   'fine-focus sealed X-ray tube'
_diffrn_source_type              'Enhance (Mo) X-ray Source'
_exptl_absorpt_coefficient_mu    2.359
_exptl_absorpt_correction_T_max  1.00000
_exptl_absorpt_correction_T_min  0.89647
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
CrysAlisPro 1.171.38.46 (Rigaku Oxford Diffraction, 2015)
Empirical absorption correction using spherical harmonics,
 implemented in SCALE3 ABSPACK scaling algorithm.
;
_exptl_crystal_colour            colourless
_exptl_crystal_colour_primary    colourless
_exptl_crystal_density_diffrn    1.618
_exptl_crystal_description       block
_exptl_crystal_F_000             624
_exptl_crystal_size_max          0.15
_exptl_crystal_size_mid          0.14
_exptl_crystal_size_min          0.11
_refine_diff_density_max         0.487
_refine_diff_density_min         -0.481
_refine_diff_density_rms         0.085
_refine_ls_abs_structure_details
;
 Flack x determined using 1288 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
;
_refine_ls_abs_structure_Flack   0.007(15)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.001
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     273
_refine_ls_number_reflns         4612
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.001
_refine_ls_R_factor_all          0.0516
_refine_ls_R_factor_gt           0.0435
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0420P)^2^] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0880
_refine_ls_wR_factor_ref         0.0922
_reflns_Friedel_coverage         0.529
_reflns_Friedel_fraction_full    0.670
_reflns_Friedel_fraction_max     0.495
_reflns_number_gt                4031
_reflns_number_total             4612
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            c8cc06199h2.cif
_cod_data_source_block           S-Eti_ZnCl2
_cod_depositor_comments
'Adding full bibliography for 7122311--7122312.cif.'
_cod_database_code               7122312
_shelx_shelxl_version_number     2018/1
_shelx_estimated_absorpt_t_max   0.781
_shelx_estimated_absorpt_t_min   0.719
_reflns_odcompleteness_completeness 99.81
_reflns_odcompleteness_iscentric 1
_reflns_odcompleteness_theta     26.32
_olex2_refinement_description
;
1. Fixed Uiso
 At 1.2 times of:
  All C(H) groups, All C(H,H) groups, All N(H,H) groups
 At 1.5 times of:
  All C(H,H,H) groups
2.a Ternary CH refined with riding coordinates:
 C5(H5), C13(H13)
2.b Secondary CH2 refined with riding coordinates:
 C10(H10A,H10B), C12(H12A,H12B), C7(H7A,H7B), C2(H2C,H2D), C4(H4C,H4D),
 C11(H11A,H11B), C3(H3A,H3B), C15(H15A,H15B)
2.c X=CH2 refined with riding coordinates:
 N4(H4A,H4B), N2(H2A,H2B)
2.d Idealised Me refined as rotating group:
 C8(H8A,H8B,H8C), C16(H16A,H16B,H16C)
;
_shelx_res_checksum              89
_olex2_submission_special_instructions 'No special instructions were received'
_oxdiff_exptl_absorpt_empirical_details
;
Empirical correction (ABSPACK) includes:
- Absorption correction using spherical harmonics
- Frame scaling
;
_oxdiff_exptl_absorpt_empirical_full_max 1.285
_oxdiff_exptl_absorpt_empirical_full_min 0.884