<i>trans</i>- and <i>cis</i>-2,5-Dimethoxy-3,6-diphenyl-3,6-dihydropyrazine
Benecke, B.; Bolte, M.; Acta Crystallographica Section C 52 (1996) 2586–2588; doi:10.1107/S0108270196006634

data_2005483
_publ_section_title
;
 <i>trans</i>- and
 <i>cis</i>-2,5-Dimethoxy-3,6-diphenyl-3,6-dihydropyrazine
;
_journal_issue                   10
_journal_name_full               'Acta Crystallographica Section C'
_journal_page_first              2586
_journal_page_last               2588
_journal_paper_doi               10.1107/S0108270196006634
_journal_volume                  52
_journal_year                    1996
_chemical_formula_iupac          'C18 H18 N2 O2'
_chemical_formula_moiety         'C18 H18 N2 O2'
_chemical_formula_sum            'C18 H18 N2 O2'
_chemical_formula_weight         294.34
_chemical_name_systematic
;
 (3RS,6SR)-2,5-dimethoxy-3,6-diphenyl-3,6-dihydropyrazine
;
_space_group_IT_number           15
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-C 2yc'
_symmetry_space_group_name_H-M   'C 1 2/c 1'
_audit_creation_method           SHELXL
_cell_angle_alpha                90.
_cell_angle_beta                 128.692(12)
_cell_angle_gamma                90.
_cell_formula_units_Z            4
_cell_length_a                   21.519(3)
_cell_length_b                   5.5068(4)
_cell_length_c                   16.422(2)
_cell_measurement_reflns_used    62
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      12.5
_cell_measurement_theta_min      10.0
_cell_volume                     1518.9(4)
_computing_cell_refinement       DIF4
_computing_data_collection       'DIF4 (Stoe & Cie, 1988a)'
_computing_data_reduction        'REDU4 (Stoe & Cie, 1988b)'
_computing_molecular_graphics    'SHELXTL-Plus (Sheldrick, 1991)'
_computing_structure_refinement  'SHELXL93 (Sheldrick, 1993)'
_computing_structure_solution    'SHELXS86 (Sheldrick, 1985)'
_diffrn_ambient_temperature      293(2)
_diffrn_measurement_device       'STOE-Siemens-AED four-circle'
_diffrn_measurement_method
'2\q/\w scans with on-line profile fitting (Clegg, 1981)'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71069
_diffrn_reflns_av_R_equivalents  0.0249
_diffrn_reflns_av_sigmaI/netI    0.0250
_diffrn_reflns_limit_h_max       19
_diffrn_reflns_limit_h_min       -25
_diffrn_reflns_limit_k_max       1
_diffrn_reflns_limit_k_min       -6
_diffrn_reflns_limit_l_max       19
_diffrn_reflns_limit_l_min       0
_diffrn_reflns_number            1978
_diffrn_reflns_theta_max         25.00
_diffrn_reflns_theta_min         3.79
_diffrn_standards_decay_%        none
_diffrn_standards_interval_count 100
_diffrn_standards_number         3
_exptl_absorpt_coefficient_mu    0.085
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.287
_exptl_crystal_density_meas      ?
_exptl_crystal_description       block
_exptl_crystal_F_000             624
_exptl_crystal_size_max          0.50
_exptl_crystal_size_mid          0.30
_exptl_crystal_size_min          0.10
_refine_diff_density_max         0.179
_refine_diff_density_min         -0.182
_refine_ls_extinction_coef       0.050(4)
_refine_ls_extinction_method     SHELXL93
_refine_ls_goodness_of_fit_all   1.110
_refine_ls_goodness_of_fit_obs   1.175
_refine_ls_hydrogen_treatment    'H atoms riding'
_refine_ls_matrix_type           full
_refine_ls_number_parameters     102
_refine_ls_number_reflns         1335
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.290
_refine_ls_restrained_S_obs      1.175
_refine_ls_R_factor_all          0.0588
_refine_ls_R_factor_obs          0.0416
_refine_ls_shift/esd_max         0.000
_refine_ls_shift/esd_mean        0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_scheme
;
calc w = 1/[\s^2^(F~o~^2^) + (0.0633P)^2^ + 0.3436P]
where P = (F~o~^2^ + 2F~c~^2^)/3
;
_refine_ls_wR_factor_all         0.1366
_refine_ls_wR_factor_obs         0.1079
_reflns_number_observed          1028
_reflns_number_total             1336
_reflns_observed_criterion       >2sigma(I)
_cod_data_source_file            cf1094.cif
_cod_data_source_block           trans
_cod_depositor_comments
;
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 
;
_cod_original_cell_volume        1519.0(4)
_cod_original_sg_symbol_H-M      'C 2/c'
_cod_database_code               2005483