Determining the crystal structure of twinned 2-methylpyrazine
Boese, Roland; Gehrke, Annette; Kapon, Moshe; Herbstein, Frank H.; Acta Crystallographica Section B 56 (2000) 677–681; doi:10.1107/S0108768199016547

data_2102095
_publ_section_title
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 Determining the crystal structure of twinned 2-methylpyrazine
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_journal_issue                   4
_journal_name_full               'Acta Crystallographica Section B'
_journal_page_first              677
_journal_page_last               681
_journal_paper_doi               10.1107/S0108768199016547
_journal_volume                  56
_journal_year                    2000
_chemical_formula_sum            'C5 H6 N2'
_chemical_formula_weight         94.12
_chemical_melting_point          242
_chemical_name_common            2-Methylpyrazine
_chemical_name_systematic        ' pyrazine, 2-methyl'
_space_group_IT_number           82
_symmetry_cell_setting           tetragonal
_symmetry_space_group_name_Hall  'I -4'
_symmetry_space_group_name_H-M   'I -4'
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            16
_cell_length_a                   13.725(2)
_cell_length_b                   13.725(2)
_cell_length_c                   10.859(2)
_cell_measurement_reflns_used    50
_cell_measurement_temperature    123(2)
_cell_measurement_theta_max      45
_cell_measurement_theta_min      3
_cell_volume                     2045.6(6)
_computing_cell_refinement
;
'Siemens P3-PC diffractometer program V.4.24'
;
_computing_data_collection
;
'Siemens P3-PC diffractometer program V.4.24'
;
_computing_data_reduction        ' Siemens XDISK V.4.20.2 1991 PC'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      123(2)
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device_type  'Nicolet R3m/V four circle diffractometer'
_diffrn_measurement_method       'Wyckoff scan mode'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     .71073
_diffrn_reflns_av_R_equivalents  .0241
_diffrn_reflns_av_sigmaI/netI    .0229
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -14
_diffrn_reflns_limit_k_max       14
_diffrn_reflns_limit_k_min       -10
_diffrn_reflns_limit_l_max       11
_diffrn_reflns_limit_l_min       0
_diffrn_reflns_number            1474
_diffrn_reflns_theta_full        22.50
_diffrn_reflns_theta_max         22.50
_diffrn_reflns_theta_min         2.10
_diffrn_standards_decay_%        .7
_diffrn_standards_interval_count 100
_diffrn_standards_number         2
_exptl_absorpt_coefficient_mu    .079
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.222
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       cylindrical
_exptl_crystal_F_000             800
_exptl_crystal_size_rad          .15
_refine_diff_density_max         .086
_refine_diff_density_min         -.124
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   -6(3)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.082
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     176
_refine_ls_number_reflns         1338
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.082
_refine_ls_R_factor_all          .0270
_refine_ls_R_factor_gt           .0257
_refine_ls_shift/su_max          .004
_refine_ls_shift/su_mean         .001
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0428P)^2^+0.2414P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_ref         .0679
_reflns_number_gt                1301
_reflns_number_total             1338
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            cf0007.cif
_cod_depositor_comments
;
The following automatic conversions were performed:
'_symmetry_cell_setting' value 'Tetragonal' changed to 'tetragonal'
according to '/home/saulius/struct/CIF-dictionaries/cif_core.dic'
dictionary named 'cif_core.dic' version 2.4.1 from 2010-06-29.

Automatic conversion script
Id: cif_fix_enum 1527 2010-12-29 10:47:43Z saulius 
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_cod_original_sg_symbol_H-M      I-4
_cod_database_code               2102095