1,4-Dihydroxyquinoxaline-2,3(1<i>H</i>,4<i>H</i>)-dione
Abu-El-Halawah, Rajab; Ali, Basem Fares; Ibrahim, Mohammad M.; Zahra, Jalal A.; Frey, Wolfgang; Acta Crystallographica Section E 64 (2008) o571–o572; doi:10.1107/S1600536808003784

data_2217788
_publ_section_title
;
 1,4-Dihydroxyquinoxaline-2,3(1<i>H</i>,4<i>H</i>)-dione
;
_journal_coeditor_code           HK2425
_journal_issue                   3
_journal_name_full               'Acta Crystallographica Section E'
_journal_page_first              o571
_journal_page_last               o572
_journal_paper_doi               10.1107/S1600536808003784
_journal_volume                  64
_journal_year                    2008
_chemical_formula_iupac          'C8 H6 N2 O4'
_chemical_formula_moiety         'C8 H6 N2 O4'
_chemical_formula_sum            'C8 H6 N2 O4'
_chemical_formula_weight         194.15
_chemical_name_systematic
;
1,4-Dihydroxyquinoxaline-2,3(1<i>H</i>,4<i>H</i>)-dione
;
_space_group_IT_number           20
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  'C 2c 2'
_symmetry_space_group_name_H-M   'C 2 2 21'
_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            4
_cell_length_a                   4.2562(6)
_cell_length_b                   17.630(3)
_cell_length_c                   10.4775(17)
_cell_measurement_reflns_used    20
_cell_measurement_temperature    294(2)
_cell_measurement_theta_max      16
_cell_measurement_theta_min      14
_cell_volume                     786.2(2)
_computing_cell_refinement
'P3/PC Data Collection Software (Siemens, 1991)'
_computing_data_collection
'P3/PC Data Collection Software (Siemens, 1991)'
_computing_data_reduction        'SHELXTL-Plus (Sheldrick, 2008)'
_computing_molecular_graphics    'SHELXTL-Plus (Sheldrick, 2008)'
_computing_publication_material
'SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2003)'
_computing_structure_refinement  'SHELXL97 (Sheldrick, 2008)'
_computing_structure_solution    'SHELXS97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      294(2)
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device_type  'Nicolet P3'
_diffrn_measurement_method       'Wyckoff scan'
_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  0.0223
_diffrn_reflns_av_sigmaI/netI    0.0268
_diffrn_reflns_limit_h_max       5
_diffrn_reflns_limit_h_min       0
_diffrn_reflns_limit_k_max       22
_diffrn_reflns_limit_k_min       0
_diffrn_reflns_limit_l_max       13
_diffrn_reflns_limit_l_min       -13
_diffrn_reflns_number            1004
_diffrn_reflns_theta_full        26.96
_diffrn_reflns_theta_max         26.96
_diffrn_reflns_theta_min         2.31
_diffrn_standards_decay_%        2
_diffrn_standards_interval_count 50
_diffrn_standards_number         3
_exptl_absorpt_coefficient_mu    0.135
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            Colourless
_exptl_crystal_density_diffrn    1.640
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       plates
_exptl_crystal_F_000             400
_exptl_crystal_size_max          0.50
_exptl_crystal_size_mid          0.20
_exptl_crystal_size_min          0.10
_refine_diff_density_max         0.115
_refine_diff_density_min         -0.152
_refine_ls_extinction_coef       0.013(2)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     'SHELXL97 (Sheldrick, 2008)'
_refine_ls_goodness_of_fit_ref   1.073
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     69
_refine_ls_number_reflns         529
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.073
_refine_ls_R_factor_all          0.0434
_refine_ls_R_factor_gt           0.0340
_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^)+(0.0208P)^2^+0.4073P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0684
_refine_ls_wR_factor_ref         0.0710
_reflns_number_gt                437
_reflns_number_total             529
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            hk2425.cif
_cod_data_source_block           I
_cod_database_code               2217788
_cod_database_fobs_code          2217788