High Z′ polymorphs have shorter C–H⋯O interactions and O–H⋯O hydrogen bonds
Babu, N. Jagadeesh; Nangia, Ashwini; CrystEngComm 9 (2007) 980–; doi:10.1039/b711739f

data_7203097
_publ_section_title
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 High Z&#x2032; polymorphs have shorter C--H&#x22EF;O interactions and
 O--H&#x22EF;O hydrogen bonds
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_journal_issue                   11
_journal_name_full               CrystEngComm
_journal_page_first              980
_journal_paper_doi               10.1039/b711739f
_journal_volume                  9
_journal_year                    2007
_chemical_formula_moiety         ' C2 H2 N O, 0.5(C4 H4 N2 O2)'
_chemical_formula_sum            'C4 H4 N2 O2'
_chemical_formula_weight         112.09
_chemical_name_common            Pyrazine-N,N'-dioxide
_chemical_name_systematic
;
Pyrazine-N,N'-dioxide
;
_chemical_temperature_decomposition 560
_space_group_IT_number           62
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  '-P 2ac 2n'
_symmetry_space_group_name_H-M   'P n m a'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            8
_cell_length_a                   11.8672(18)
_cell_length_b                   12.2217(19)
_cell_length_c                   6.4287(10)
_cell_measurement_reflns_used    1512
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      25.94
_cell_measurement_theta_min      3.33
_cell_volume                     932.4(2)
_computing_cell_refinement       'Bruker SMART'
_computing_data_collection       'Bruker SMART'
_computing_data_reduction        'Bruker SAINT'
_computing_molecular_graphics    'Bruker SHELXTL'
_computing_publication_material  'Bruker SHELXTL'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device_type  'CCD area detector'
_diffrn_measurement_method       'phi and omega scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0312
_diffrn_reflns_av_sigmaI/netI    0.0217
_diffrn_reflns_limit_h_max       12
_diffrn_reflns_limit_h_min       -14
_diffrn_reflns_limit_k_max       15
_diffrn_reflns_limit_k_min       -14
_diffrn_reflns_limit_l_max       7
_diffrn_reflns_limit_l_min       -6
_diffrn_reflns_number            4790
_diffrn_reflns_theta_full        26.01
_diffrn_reflns_theta_max         26.01
_diffrn_reflns_theta_min         3.33
_exptl_absorpt_coefficient_mu    0.131
_exptl_absorpt_correction_T_max  0.9922
_exptl_absorpt_correction_T_min  0.9482
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'Bruker AXS SADABS program'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.597
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       plate
_exptl_crystal_F_000             464
_exptl_crystal_size_max          0.41
_exptl_crystal_size_mid          0.21
_exptl_crystal_size_min          0.06
_refine_diff_density_max         0.223
_refine_diff_density_min         -0.314
_refine_diff_density_rms         0.060
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.151
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     85
_refine_ls_number_reflns         956
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.151
_refine_ls_R_factor_all          0.0874
_refine_ls_R_factor_gt           0.0605
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0730P)^2^+0.2522P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1439
_refine_ls_wR_factor_ref         0.1584
_reflns_number_gt                643
_reflns_number_total             956
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            b711739f.txt
_cod_data_source_block           pnma
_cod_depositor_comments
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The following automatic conversions were performed:
'_symmetry_cell_setting' value 'Orthorhombic' changed to 'orthorhombic'
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 

The following automatic conversions were performed:

'_chemical_melting_point' tag was changed to
'_chemical_temperature_decomposition' since the value had been '560K
(decomp) '. The value '560K (decomp) ' was changed to '560'.

Automatic conversion script
Id: cif_fix_values 1646 2011-03-28 12:23:43Z adriana 
;
_cod_original_sg_symbol_H-M      'Pnma '
_cod_database_code               7203097