The pyridinium-betaine of squaric acid
Tsonko Kolev; Denitsa Yancheva; Boris Shivachev; Rosica Petrova; Acta Crystallographica Section E 63 (2007) o3259–o3259; doi:10.1107/S1600536807028887

data_2214284
_publ_section_title
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 The pyridinium-betaine of squaric acid
;
_journal_coeditor_code           IS2179
_journal_issue                   7
_journal_name_full               'Acta Crystallographica Section E'
_journal_page_first              o3259
_journal_page_last               o3259
_journal_paper_doi               10.1107/S1600536807028887
_journal_volume                  63
_journal_year                    2007
_chemical_formula_moiety         'C9 H5 N O3'
_chemical_formula_sum            'C9 H5 N O3'
_chemical_formula_weight         175.14
_chemical_name_common            'Pyridinium-betaine of squaric acid'
_chemical_name_systematic
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3,4-dioxo-2-(pyridinium-1-yl)cyclobut-1-enolate
;
_space_group_IT_number           60
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  '-P 2n 2ab'
_symmetry_space_group_name_H-M   'P b c n'
_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                   5.0654(2)
_cell_length_b                   18.8003(17)
_cell_length_c                   8.1609(4)
_cell_measurement_reflns_used    22
_cell_measurement_temperature    290(2)
_cell_measurement_theta_max      19.60
_cell_measurement_theta_min      19.28
_cell_volume                     777.17(9)
_computing_cell_refinement       'CAD-4 EXPRESS'
_computing_data_collection       'CAD-4 EXPRESS (Enraf--Nonius, 1994)'
_computing_data_reduction        'XCAD4 (Harms & Wocadlo, 1995)'
_computing_molecular_graphics
'ORTEP-3 for Windows (Farrugia, 1997) and Mercury (Bruno <i>et al.</i>, 2002)'
_computing_publication_material  'WinGX (Farrugia, 1999)'
_computing_structure_refinement  'SHELXL97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      290(2)
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device       '\k-geometry diffractometer'
_diffrn_measurement_device_type  'Enraf--Nonius CAD-4'
_diffrn_measurement_method       'Non-profiled \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  0.0701
_diffrn_reflns_av_sigmaI/netI    0.0418
_diffrn_reflns_limit_h_max       6
_diffrn_reflns_limit_h_min       0
_diffrn_reflns_limit_k_max       24
_diffrn_reflns_limit_k_min       -24
_diffrn_reflns_limit_l_max       10
_diffrn_reflns_limit_l_min       -10
_diffrn_reflns_number            3425
_diffrn_reflns_theta_full        27.91
_diffrn_reflns_theta_max         27.91
_diffrn_reflns_theta_min         2.17
_diffrn_standards_decay_%        -5
_diffrn_standards_interval_time  120
_diffrn_standards_number         3
_exptl_absorpt_coefficient_mu    0.115
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            yellow
_exptl_crystal_density_diffrn    1.497
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prism
_exptl_crystal_F_000             360
_exptl_crystal_size_max          0.40
_exptl_crystal_size_mid          0.36
_exptl_crystal_size_min          0.36
_refine_diff_density_max         0.154
_refine_diff_density_min         -0.196
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.035
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     63
_refine_ls_number_reflns         942
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.035
_refine_ls_R_factor_all          0.1072
_refine_ls_R_factor_gt           0.0534
_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^)+(0.0456P)^2^+0.3645P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1135
_refine_ls_wR_factor_ref         0.1335
_reflns_number_gt                559
_reflns_number_total             942
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            is2179.cif
_cod_data_source_block           I
_cod_depositor_comments
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The following automatic conversions were performed:

'_chemical_melting_point' value 'not measured' was changed to '?' -
the value is undefined or not given.

Automatic conversion script
Id: cif_fix_values 1646 2011-03-28 12:23:43Z adriana 

The following automatic conversions were performed:

'_chemical_melting_point' value 'not measured' was changed to '?' -
the value is undefined or not given.

Automatic conversion script
Id: cif_fix_values 1715 2011-07-08 13:25:40Z adriana 
;
_cod_original_sg_symbol_Hall     '-P 2n 2ab '
_cod_database_code               2214284
_cod_database_fobs_code          2214284