Reducing the background of ultra-low-temperature X-ray diffraction data through new methods and advanced materials
McMonagle, Charles James; Probert, Michael Richard; Journal of Applied Crystallography 52 (2019) 445–450; doi:10.1107/S1600576719003078

data_2300647
_publ_section_title
;
 Reducing the background of ultra-low-temperature X-ray diffraction data
 through new methods and advanced materials
;
_journal_issue                   2
_journal_name_full               'Journal of Applied Crystallography'
_journal_page_first              445
_journal_page_last               450
_journal_paper_doi               10.1107/S1600576719003078
_journal_volume                  52
_journal_year                    2019
_chemical_absolute_configuration rm
_chemical_formula_moiety         'C6 H8 O6'
_chemical_formula_sum            'C6 H8 O6'
_chemical_formula_weight         176.12
_chemical_name_common            'Vitamin C'
_chemical_name_systematic        'L-ascorbic acid'
_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             2019-01-17
_audit_creation_method
;
Olex2 1.2
(compiled 2018.05.29 svn.r3508 for OlexSys, GUI svn.r5506)
;
_cell_angle_alpha                90
_cell_angle_beta                 99.356(3)
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   6.4196(2)
_cell_length_b                   6.3619(3)
_cell_length_c                   17.1568(6)
_cell_measurement_reflns_used    1182
_cell_measurement_temperature    292.36
_cell_measurement_theta_max      23.645
_cell_measurement_theta_min      2.406
_cell_volume                     691.38(5)
_computing_cell_refinement       'SAINT V8.38A (?, 2016)'
_computing_data_reduction        'SAINT V8.38A (?, 2016)'
_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      292.36
_diffrn_detector                 'CCD area detector'
_diffrn_detector_type            'Bruker APEXII area detector'
_diffrn_measured_fraction_theta_full 0.941
_diffrn_measured_fraction_theta_max 0.941
_diffrn_measurement_device       'XIPHOS four-circle diffractometer'
_diffrn_measurement_device_type  'Bruker APEX-II CCD'
_diffrn_measurement_method       '\f scans'
_diffrn_radiation_collimation    focused
_diffrn_radiation_monochromator  'multilayer optics'
_diffrn_radiation_probe          x-ray
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0655
_diffrn_reflns_av_unetI/netI     0.0778
_diffrn_reflns_Laue_measured_fraction_full 0.941
_diffrn_reflns_Laue_measured_fraction_max 0.941
_diffrn_reflns_limit_h_max       7
_diffrn_reflns_limit_h_min       -7
_diffrn_reflns_limit_k_max       7
_diffrn_reflns_limit_k_min       -7
_diffrn_reflns_limit_l_max       19
_diffrn_reflns_limit_l_min       -19
_diffrn_reflns_number            6127
_diffrn_reflns_point_group_measured_fraction_full 0.951
_diffrn_reflns_point_group_measured_fraction_max 0.950
_diffrn_reflns_theta_full        24.415
_diffrn_reflns_theta_max         24.415
_diffrn_reflns_theta_min         1.203
_diffrn_source                   'rotating anode'
_diffrn_source_target            Mo
_diffrn_source_type              'Bruker TXS with Helios Optics'
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.156
_exptl_absorpt_correction_T_max  0.7451
_exptl_absorpt_correction_T_min  0.6883
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
'SADABS-2016/2 (Bruker,2016/2) was used for absorption correction.'
_exptl_crystal_colour            'clear colourless'
_exptl_crystal_colour_lustre     clear
_exptl_crystal_colour_primary    colourless
_exptl_crystal_density_diffrn    1.692
_exptl_crystal_description       block
_exptl_crystal_F_000             368
_exptl_crystal_preparation       'As supplied'
_exptl_crystal_size_max          0.035
_exptl_crystal_size_mid          0.035
_exptl_crystal_size_min          0.01
_refine_diff_density_max         0.193
_refine_diff_density_min         -0.225
_refine_diff_density_rms         0.050
_refine_ls_abs_structure_details
;
 Flack x determined using 500 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
;
_refine_ls_abs_structure_Flack   -0.6(10)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.960
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     225
_refine_ls_number_reflns         2183
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      0.959
_refine_ls_R_factor_all          0.0883
_refine_ls_R_factor_gt           0.0436
_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^)+(0.0284P)^2^] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0714
_refine_ls_wR_factor_ref         0.0828
_reflns_Friedel_coverage         0.836
_reflns_Friedel_fraction_full    0.963
_reflns_Friedel_fraction_max     0.962
_reflns_number_gt                1423
_reflns_number_total             2183
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            kc5091sup1.cif
_cod_data_source_block           Collection_2_vitamin_C
_cod_database_code               2300647
_cod_database_fobs_code          2300647
_shelx_shelxl_version_number     2018/3
_olex2_refinement_description
;
1. Fixed Uiso
 At 1.2 times of:
  All C(H) groups, All C(H,H) groups
 At 1.5 times of:
  All O(H) groups
2.a Ternary CH refined with riding coordinates:
 C2(H2A), C3(H3A), C8(H8A), C9(H9A)
2.b Secondary CH2 refined with riding coordinates:
 C1(H1A,H1B), C7(H7A,H7B)
2.c Idealised tetrahedral OH refined as rotating group:
 O1(H1), O2(H2), O3(H3), O4(H4), O7(H7), O8(H8), O9(H9), O10(H10)
;
_shelx_res_checksum              22202
_shelx_hkl_checksum              27751
_olex2_date_sample_data_collection 2018-11-10
_olex2_date_sample_submission    2018-11-10
_olex2_submission_special_instructions 'No special instructions were received'