Pyridinium oxalate(1–) oxalic acid dihydrate
K. Rajagopal; R. V. Krishnakumar; S. Natarajan; Acta Crystallographica Section E 59 (2003) o742–o744; doi:10.1107/S1600536803009164

data_2202083
_publ_section_title
;
 Pyridinium oxalate(1--) oxalic acid dihydrate
;
_journal_issue                   6
_journal_name_full               'Acta Crystallographica Section E'
_journal_page_first              o742
_journal_page_last               o744
_journal_paper_doi               10.1107/S1600536803009164
_journal_volume                  59
_journal_year                    2003
_chemical_formula_iupac          'C5 H6 N 1+, C2 H2 O4 1-, C2 H O4, 2H2 O'
_chemical_formula_moiety         'C5 H6 N 1+, C2 H2 O4 1-, C2 H O4, 2H2 O'
_chemical_formula_sum            'C9 H13 N O10'
_chemical_formula_weight         295.20
_chemical_name_common            'Pyridinuim oxalate oxalic acid dihydrate'
_chemical_name_systematic
;
 Pyridinium oxalate oxalic acid dihydrate
;
_space_group_IT_number           2
_symmetry_cell_setting           triclinic
_symmetry_space_group_name_Hall  '-P 1'
_symmetry_space_group_name_H-M   'P -1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                84.36(2)
_cell_angle_beta                 79.54(4)
_cell_angle_gamma                74.71(6)
_cell_formula_units_Z            2
_cell_length_a                   6.992(7)
_cell_length_b                   9.539(2)
_cell_length_c                   10.098(2)
_cell_measurement_reflns_used    25
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      25.0
_cell_measurement_theta_min      2.0
_cell_volume                     638.0(7)
_computing_cell_refinement       'CAD-4 Software'
_computing_data_collection       'CAD-4 Software (Enraf-Nonius, 1989)'
_computing_data_reduction        'CAD-4 Software'
_computing_molecular_graphics    'PLATON (Spek, 1999)'
_computing_publication_material  SHELXL97
_computing_structure_refinement  'SHELXL97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS97 (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  'Enraf-Nonius CAD-4'
_diffrn_measurement_method       \w-2\q
_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  0.0061
_diffrn_reflns_av_sigmaI/netI    0.0117
_diffrn_reflns_limit_h_max       8
_diffrn_reflns_limit_h_min       0
_diffrn_reflns_limit_k_max       11
_diffrn_reflns_limit_k_min       -10
_diffrn_reflns_limit_l_max       11
_diffrn_reflns_limit_l_min       -11
_diffrn_reflns_number            2451
_diffrn_reflns_theta_full        24.97
_diffrn_reflns_theta_max         24.97
_diffrn_reflns_theta_min         2.05
_diffrn_standards_decay_%        <1
_diffrn_standards_interval_count 200
_diffrn_standards_number         2
_exptl_absorpt_coefficient_mu    0.143
_exptl_absorpt_correction_T_max  0.971
_exptl_absorpt_correction_T_min  0.948
_exptl_absorpt_correction_type   '\y scan'
_exptl_absorpt_process_details   '(North et al., 1968)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.537
_exptl_crystal_density_meas      1.55
_exptl_crystal_density_method
'flotation in a mixture of xylene and bromoform'
_exptl_crystal_description       prismatic
_exptl_crystal_F_000             308
_exptl_crystal_size_max          0.40
_exptl_crystal_size_mid          0.35
_exptl_crystal_size_min          0.17
_refine_diff_density_max         0.256
_refine_diff_density_min         -0.208
_refine_ls_extinction_coef       0.017(5)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     SHELXL97
_refine_ls_goodness_of_fit_ref   1.092
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     198
_refine_ls_number_reflns         2250
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.092
_refine_ls_R_factor_all          0.0430
_refine_ls_R_factor_gt           0.0370
_refine_ls_shift/su_max          <0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w = 1/[\s^2^(Fo^2^)+(0.0645P)^2^+0.1652P] where P = (Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1059
_refine_ls_wR_factor_ref         0.1127
_reflns_number_gt                1946
_reflns_number_total             2250
_reflns_threshold_expression     I>2s(I)
_cod_data_source_file            na6224.cif
_cod_data_source_block           I
_cod_database_code               2202083
_cod_database_fobs_code          2202083