General rules for the packing of hydrogen-bonded crystals as derived from the analysis of squaric acid anions: aminoaromatic nitrogen base co-crystals
Bertolasi, Valerio; Gilli, Paola; Ferretti, Valeria; Gilli, Gastone; Acta Crystallographica Section B 57 (2001) 591–598; doi:10.1107/S010876810100814X

data_2103720
_publ_section_title
;
 General rules for the packing of hydrogen-bonded crystals as derived
 from the analysis of squaric acid anions: aminoaromatic nitrogen base
 co-crystals
;
_journal_issue                   4
_journal_name_full               'Acta Crystallographica Section B'
_journal_page_first              591
_journal_page_last               598
_journal_paper_doi               10.1107/S010876810100814X
_journal_volume                  57
_journal_year                    2001
_chemical_formula_moiety         'C5 H7 N2, C4 H O4'
_chemical_formula_sum            'C9 H8 N2 O4'
_chemical_formula_weight         208.17
_chemical_name_systematic
;
4-aminopyridinium . hydrogen squarate, 1:1
;
_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'
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 97.95(2)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   10.283(3)
_cell_length_b                   7.0680(10)
_cell_length_c                   12.642(2)
_cell_measurement_reflns_used    25
_cell_measurement_temperature    296(2)
_cell_measurement_theta_max      13
_cell_measurement_theta_min      9
_cell_volume                     910.0(3)
_computing_cell_refinement       'CAD4 (Enraf-Nonius, 1984)'
_computing_data_collection       'CAD4 (Enraf-Nonius, 1984)'
_computing_data_reduction        'MolEN (Fair, 1990; Enraf-Nonius, 1990)'
_computing_molecular_graphics    'ORTEPII (Johnson, 1976)'
_computing_publication_material
;
PARST (Nardelli, 1983, 1995); SHELXL-97 (Sheldrick, 1997)
;
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SIR92 (Altomare et al., 1994)'
_diffrn_ambient_temperature      296(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     .71073
_diffrn_reflns_av_R_equivalents  .030
_diffrn_reflns_av_sigmaI/netI    .0160
_diffrn_reflns_limit_h_max       14
_diffrn_reflns_limit_h_min       0
_diffrn_reflns_limit_k_max       9
_diffrn_reflns_limit_k_min       0
_diffrn_reflns_limit_l_max       17
_diffrn_reflns_limit_l_min       -17
_diffrn_reflns_number            2995
_diffrn_reflns_theta_full        29.94
_diffrn_reflns_theta_max         30
_diffrn_reflns_theta_min         2.00
_diffrn_standards_decay_%        0
_diffrn_standards_interval_time  120
_diffrn_standards_number         3
_exptl_absorpt_coefficient_mu    .122
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.519
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       irregular
_exptl_crystal_F_000             432
_exptl_crystal_size_max          .60
_exptl_crystal_size_mid          .36
_exptl_crystal_size_min          .28
_refine_diff_density_max         .367
_refine_diff_density_min         -.175
_refine_ls_extinction_coef       .036(5)
_refine_ls_extinction_method     SHELXL
_refine_ls_goodness_of_fit_ref   1.072
_refine_ls_hydrogen_treatment    refall
_refine_ls_matrix_type           full
_refine_ls_number_parameters     169
_refine_ls_number_reflns         2647
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.072
_refine_ls_R_factor_all          .0468
_refine_ls_R_factor_gt           .0379
_refine_ls_shift/su_max          .006
_refine_ls_shift/su_mean         .001
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0708P)^2^+0.1027P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_ref         .1186
_reflns_number_gt                2216
_reflns_number_total             2647
_reflns_threshold_expression     I>2sigma(I)
_cod_data_source_file            na0121.cif
_cod_data_source_block           3
_cod_original_sg_symbol_H-M      'P 21/c'
_cod_database_code               2103720
_cod_database_fobs_code          2103720