Stabilization of D5h and C2v valence tautomers of the croconate dianion.
Lam, Chi-Keung; Cheng, Mei-Fun; Li, Chi-Lun; Zhang, Jie-Peng; Chen, Xiao-Ming; Li, Wai-Kee; Mak, Thomas C W; Chemical communications (Cambridge, England)  (2004) 448–449; doi:10.1039/b312545a

data_7102461
_publ_section_title
;
 Stabilization of D5h and C2v valence tautomers of the croconate
 dianion.
;
_journal_issue                   4
_journal_name_full
'Chemical communications (Cambridge, England)'
_journal_page_first              448
_journal_page_last               449
_journal_paper_doi               10.1039/b312545a
_journal_year                    2004
_chemical_formula_moiety         '[(n-C4H9)4N+]2(C5O5)2-.3(CH3NH)2CO'
_chemical_formula_sum            'C46 H96 N8 O8'
_chemical_formula_weight         889.31
_chemical_melting_point          424.1(10)
_chemical_name_common
'bis(tetra-n-butylammonium) croconate-1,3-dimethylurea (1/3) '
_chemical_name_systematic
;
bis(tetra-n-butylammonium) croconate-1,3-dimethylurea (1/3)
;
_space_group_IT_number           15
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-C 2yc'
_symmetry_space_group_name_H-M   'C 1 2/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                 93.204(18)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   25.211(4)
_cell_length_b                   13.5697(19)
_cell_length_c                   15.775(2)
_cell_measurement_temperature    123
_cell_volume                     5388.4(14)
_computing_cell_refinement
;
SAINT-PLUS for Windows NT, Ver. 5.0, Bruker AXS Inc., 
Madison, Wisconsin, USA, 1997.
;
_computing_data_collection
'SMART for Windows NT, Bruker AXS Inc., Madison, Wisconsin, USA, 1997.'
_computing_data_reduction
;SAINT-PLUS for Windows NT, Ver. 5.0, Bruker AXS Inc., Madison,
Wisconsin, USA, 1997.
;
_computing_molecular_graphics
;
XP-Interactive Molecular Graphics, Ver. 5.1, Bruker AXS Inc., Madison,
Wisconsin, USA, 1998.
;
_computing_publication_material
'SHELXTL-Bruker AXS Inc., Madison, Wisconsin, USA, 1998.'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      123
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.999
_diffrn_measurement_device_type  ' Smart Apex CCD'
_diffrn_measurement_method       ' omega 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  0.0222
_diffrn_reflns_av_sigmaI/netI    0.0212
_diffrn_reflns_limit_h_max       31
_diffrn_reflns_limit_h_min       -31
_diffrn_reflns_limit_k_max       16
_diffrn_reflns_limit_k_min       -16
_diffrn_reflns_limit_l_max       19
_diffrn_reflns_limit_l_min       -19
_diffrn_reflns_number            27470
_diffrn_reflns_theta_full        26.00
_diffrn_reflns_theta_max         26.00
_diffrn_reflns_theta_min         2.85
_exptl_absorpt_coefficient_mu    0.075
_exptl_absorpt_correction_T_max  1.000000
_exptl_absorpt_correction_T_min  0.894441
_exptl_absorpt_correction_type   SADABS
_exptl_crystal_colour            '  pale yellow '
_exptl_crystal_density_diffrn    1.096
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             1968
_exptl_crystal_size_max          0.43
_exptl_crystal_size_mid          0.35
_exptl_crystal_size_min          0.35
_refine_diff_density_max         0.330
_refine_diff_density_min         -0.258
_refine_diff_density_rms         0.043
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.035
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     282
_refine_ls_number_reflns         5304
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.035
_refine_ls_R_factor_all          0.0515
_refine_ls_R_factor_gt           0.0466
_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^)+(0.0736P)^2^+3.5807P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1284
_refine_ls_wR_factor_ref         0.1337
_reflns_number_gt                4687
_reflns_number_total             5304
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            b312545a.txt
_cod_data_source_block           compound(2)
_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.

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

The following automatic conversions were performed:

'_diffrn_ambient_temperature' value '123K' was changed to '123' - the
value should be numeric and without a unit designator.

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

'_chemical_melting_point' tag was changed to
'_chemical_temperature_decomposition' since the value had been given
as ' 150-152 deg. (dec) '. The value ' 150-152 deg. (dec) ' was changed 
to '424.1(10)' - it was converted from degrees Celsius(C) to Kelvins(K),
the average value was taken and precision was estimated.

Adriana Da\<skevi\<c, 2011-06-14
;
_cod_original_sg_symbol_H-M      C2/c
_cod_database_code               7102461