4-Methoxypyridinium betaine of squaric acid
T. Kolev; R. Wortmann; M. Spiteller; W. S. Sheldrick; H. Mayer-Figge; Acta Crystallographica Section E 60 (2004) o1449–o1450; doi:10.1107/S1600536804018379

data_2203987
_publ_section_title
;
 4-Methoxypyridinium betaine of squaric acid
;
_journal_issue                   8
_journal_name_full               'Acta Crystallographica Section E'
_journal_page_first              o1449
_journal_page_last               o1450
_journal_paper_doi               10.1107/S1600536804018379
_journal_volume                  60
_journal_year                    2004
_chemical_formula_iupac          'C10 H7 N O4'
_chemical_formula_moiety         'C10 H7 N O4'
_chemical_formula_sum            'C10 H7 N O4'
_chemical_formula_weight         205.17
_chemical_name_common            4-methoxypyridinium-3-squarate
_chemical_name_systematic
;
2-(4-methoxypyridinio)-3,4-dioxocyclobut-1-en-1-olate
;
_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'
_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                 96.69(3)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   4.5810(9)
_cell_length_b                   11.744(2)
_cell_length_c                   16.594(3)
_cell_measurement_reflns_used    14
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      14.6
_cell_measurement_theta_min      7.4
_cell_volume                     886.7(3)
_computing_cell_refinement       'R3m/V User's Guide'
_computing_data_collection       'R3m/V User's Guide (Siemens, 1989)'
_computing_data_reduction        'XDISK (Siemens, 1989)'
_computing_molecular_graphics    'SHELXTL-Plus (Sheldrick, 1995)'
_computing_publication_material  SHELXL97
_computing_structure_refinement  'SHELXL97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.996
_diffrn_measured_fraction_theta_max 0.996
_diffrn_measurement_device_type  'Siemens P4 four-circle'
_diffrn_measurement_method       'Profile-fitted w'
_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  0.0196
_diffrn_reflns_av_sigmaI/netI    0.0316
_diffrn_reflns_limit_h_max       5
_diffrn_reflns_limit_h_min       0
_diffrn_reflns_limit_k_max       13
_diffrn_reflns_limit_k_min       0
_diffrn_reflns_limit_l_max       19
_diffrn_reflns_limit_l_min       -19
_diffrn_reflns_number            1757
_diffrn_reflns_theta_full        25.00
_diffrn_reflns_theta_max         25.00
_diffrn_reflns_theta_min         3.02
_diffrn_standards_decay_%        2
_diffrn_standards_interval_count 100
_diffrn_standards_number         3
_exptl_absorpt_coefficient_mu    0.121
_exptl_absorpt_correction_T_max  0.98076
_exptl_absorpt_correction_T_min  0.96274
_exptl_absorpt_correction_type   psi-scan
_exptl_absorpt_process_details   '(XPREP in SHELXTL-Plus; Sheldrick, 1995)'
_exptl_crystal_colour            yellow
_exptl_crystal_density_diffrn    1.537
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       needle
_exptl_crystal_F_000             424
_exptl_crystal_size_max          0.57
_exptl_crystal_size_mid          0.27
_exptl_crystal_size_min          0.17
_refine_diff_density_max         0.150
_refine_diff_density_min         -0.138
_refine_ls_extinction_coef       0.0093(19)
_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   1.026
_refine_ls_hydrogen_treatment    refU
_refine_ls_matrix_type           full
_refine_ls_number_parameters     142
_refine_ls_number_reflns         1553
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.026
_refine_ls_R_factor_all          0.0785
_refine_ls_R_factor_gt           0.0441
_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^)+(0.0502P)^2^+0.1372P] where P = (Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0929
_refine_ls_wR_factor_ref         0.1073
_reflns_number_gt                1021
_reflns_number_total             1553
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            bt6496.cif
_cod_data_source_block           I
_cod_depositor_comments
;
The following automatic conversions were performed:
'_symmetry_cell_setting' value 'Monoclinic' changed to 'monoclinic'
according to '/home/saulius/struct/CIF-dictionaries/cif_core.dic'
dictionary named 'cif_core.dic' version 2.4.1 from
2010-06-29.

'_exptl_absorpt_correction_type' value 'Psi-scan' changed to
'psi-scan' according to
'/home/saulius/struct/CIF-dictionaries/cif_core.dic' dictionary named
'cif_core.dic' version 2.4.1 from 2010-06-29.

Automatic conversion script
Id: cif_fix_enum 1527 2010-12-29 10:47:43Z saulius 

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.

'_symmetry_cell_setting' value
'Monoclinic' changed to 'monoclinic' according to
/home/saulius/struct/CIF-dictionaries/cif_core.dic dictionary named
'cif_core.dic' version 2.4.1 from
2010-06-29.

'_exptl_absorpt_correction_type' value 'Psi-scan'
changed to 'psi-scan' according to
/home/saulius/struct/CIF-dictionaries/cif_core.dic dictionary named
'cif_core.dic' version 2.4.1 from 2010-06-29.

Automatic conversion script
Id: cif_fix_values 1715 2011-07-08 13:25:40Z adriana 
;
_cod_original_cell_volume        886.6(3)
_cod_original_sg_symbol_H-M      'P 21/c'
_cod_database_code               2203987
_cod_database_fobs_code          2203987