Dimorphism of 2,3,5,6-tetraphenylpyrazine
Bartnik, Romuald; Faure, René; Gebicki, Krzysztof; Acta Crystallographica Section C 55 (1999) 1034–1037; doi:10.1107/S0108270199002450

data_2008581
_publ_section_title
;
 Dimorphism of 2,3,5,6-tetraphenylpyrazine
;
_journal_issue                   6
_journal_name_full               'Acta Crystallographica Section C'
_journal_page_first              1034
_journal_page_last               1037
_journal_paper_doi               10.1107/S0108270199002450
_journal_volume                  55
_journal_year                    1999
_chemical_formula_moiety         'C28 H20 N2'
_chemical_formula_structural     'C28 H20 N2'
_chemical_formula_sum            'C28 H20 N2'
_chemical_formula_weight         384.48
_chemical_name_systematic        '2,3,5,6-tetraphenylpyrazine (\a form)'
_space_group_IT_number           14
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-P 2ybc'
_symmetry_space_group_name_H-M   'P 1 21/c 1'
_cell_angle_alpha                90
_cell_angle_beta                 134.450(10)
_cell_angle_gamma                90
_cell_formula_units_Z            2
_cell_length_a                   15.210(2)
_cell_length_b                   5.5390(6)
_cell_length_c                   17.192(2)
_cell_measurement_reflns_used    25
_cell_measurement_temperature    291
_cell_measurement_theta_max      57.50
_cell_measurement_theta_min      19.31
_cell_volume                     1034.0(3)
_computing_cell_refinement       'CAD4 Software'
_computing_data_collection       'CAD4 Software (Enraf Nonius, 1985)'
_computing_data_reduction        'SDP (Frenz, 1982)'
_computing_molecular_graphics    'ORTEP (Johnson, 1965) '
_computing_publication_material  'PLATON (Spek, 1990)'
_computing_structure_refinement  SDP
_computing_structure_solution    SDP
_diffrn_ambient_temperature      291
_diffrn_measurement_device       'Enraf-Nonius CAD4'
_diffrn_measurement_method       '\w--5/3\q scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_type           'Cu K\a'
_diffrn_radiation_wavelength     1.54056
_diffrn_reflns_av_R_equivalents  0.025
_diffrn_reflns_limit_h_max       18
_diffrn_reflns_limit_h_min       0
_diffrn_reflns_limit_k_max       6
_diffrn_reflns_limit_k_min       0
_diffrn_reflns_limit_l_max       15
_diffrn_reflns_limit_l_min       -21
_diffrn_reflns_number            1956
_diffrn_reflns_reduction_process
;
 ?
;
_diffrn_reflns_theta_max         73.0
_diffrn_reflns_theta_min         1.0
_diffrn_standards_decay_%        3.0
_diffrn_standards_interval_time  60
_diffrn_standards_number         3
_exptl_absorpt_coefficient_mu    0.56
_exptl_absorpt_correction_T_max  0.874
_exptl_absorpt_correction_T_min  0.816
_exptl_absorpt_correction_type   '\y scan'
_exptl_absorpt_process_details   ' (North et al., 1968)  '
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.235
_exptl_crystal_density_meas      ?
_exptl_crystal_description       flat
_exptl_crystal_F_000             404
_exptl_crystal_size_max          0.60
_exptl_crystal_size_mid          0.40
_exptl_crystal_size_min          0.24
_refine_diff_density_max         0.296
_refine_diff_density_min         -0.260
_refine_ls_abs_structure_details
;
 ?
;
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.9
_refine_ls_hydrogen_treatment    noref
_refine_ls_matrix_type           full
_refine_ls_number_parameters     137
_refine_ls_number_reflns         1915
_refine_ls_R_factor_obs          .060
_refine_ls_shift/su_max          0.01
_refine_ls_structure_factor_coef F
_refine_ls_weighting_details     'w = 4F~O~^2^[\s^2^(I) + (0.12F~O~^2^)^2^]^-1^'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_obs         .137
_reflns_number_observed          1915
_reflns_number_total             1956
_reflns_observed_criterion       ' I~net~> 0 '
_cod_data_source_file            ln1076.cif
_cod_data_source_block           alpha
_cod_depositor_comments
;
The following automatic conversions were performed:
'_symmetry_cell_setting' value 'Monoclinic' changed to 'monoclinic'
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:

'_symmetry_cell_setting' value 'Monoclinic' changed to 'monoclinic'
according to /home/saulius/struct/CIF-dictionaries/cif_core.dic
dictionary named 'cif_core.dic' version 2.4.1 from
2010-06-29.

'_refine_ls_hydrogen_treatment' value ' noref ' changed
to 'noref' 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_values 1715 2011-07-08 13:25:40Z adriana 

The following automatic conversions were performed:

'_exptl_crystal_density_meas' value 'Not measured' was changed to '?'
- the value is perceived as not measured.

Automatic conversion script
Id: cif_fix_values 3008 2015-01-20 13:52:24Z robertas 

The following automatic conversions were performed:

'_refine_ls_weighting_scheme' value ' w = 4F~O~^2^[\s^2^(I) +
(0.12F~O~^2^)^2^]^-1^ ' was changed to 'calc'. New tag
'_refine_ls_weighting_details' was created. The value of the new tag
was set to 'w = 4F~O~^2^[\s^2^(I) + (0.12F~O~^2^)^2^]^-1^'.

Automatic conversion script
Id: cif_fix_values 3143 2015-03-26 13:38:13Z robertas 
;
_cod_original_sg_symbol_H-M      'P 21/c'
_cod_database_code               2008581