Reversible solid-state interconversion of rhodizonic acid H2C6O6 into H6C6O8 and the solid-state structure of the rhodizonate dianion C6O62– (aromatic or non-aromatic?)
Braga, Dario; Cojazzi, Gianna; Maini, Lucia; Grepioni, Fabrizia; New Journal of Chemistry 25 (2001) 1221–; doi:10.1039/b107317f

data_7051225
_publ_section_title
;
 Reversible solid-state interconversion of rhodizonic acid H2C6O6 into
 H6C6O8 and the solid-state structure of the rhodizonate dianion
 C6O62-- (aromatic or non-aromatic?)
;
_journal_issue                   10
_journal_name_full               'New Journal of Chemistry'
_journal_page_first              1221
_journal_paper_doi               10.1039/b107317f
_journal_volume                  25
_journal_year                    2001
_chemical_formula_sum            'C6 H6 O8'
_chemical_formula_weight         206.11
_chemical_name_common            'Rhodizonic acid dihydrate'
_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                 91.796(6)
_cell_angle_gamma                90.00
_cell_formula_units_Z            8
_cell_length_a                   11.2163(13)
_cell_length_b                   9.6120(12)
_cell_length_c                   12.786(2)
_cell_measurement_temperature    223(2)
_cell_volume                     1377.8(3)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      223(2)
_diffrn_measured_fraction_theta_full 0.923
_diffrn_measured_fraction_theta_max 0.923
_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  0.1276
_diffrn_reflns_av_sigmaI/netI    0.1551
_diffrn_reflns_limit_h_max       17
_diffrn_reflns_limit_h_min       -12
_diffrn_reflns_limit_k_max       14
_diffrn_reflns_limit_k_min       -14
_diffrn_reflns_limit_l_max       19
_diffrn_reflns_limit_l_min       -19
_diffrn_reflns_number            9624
_diffrn_reflns_theta_full        33.95
_diffrn_reflns_theta_max         33.95
_diffrn_reflns_theta_min         2.79
_exptl_absorpt_coefficient_mu    0.193
_exptl_absorpt_correction_type   'Bruker absorption correction'
_exptl_crystal_density_diffrn    1.987
_exptl_crystal_density_method    'not measured'
_exptl_crystal_F_000             848
_refine_diff_density_max         0.526
_refine_diff_density_min         -0.401
_refine_diff_density_rms         0.091
_refine_ls_extinction_coef       0.0029(7)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     SHELXL
_refine_ls_goodness_of_fit_ref   0.730
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     152
_refine_ls_number_reflns         2589
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      0.730
_refine_ls_R_factor_all          0.1436
_refine_ls_R_factor_gt           0.0592
_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^)+(0.0731P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1194
_refine_ls_wR_factor_ref         0.1462
_reflns_number_gt                1219
_reflns_number_total             2589
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            b107317f.txt
_cod_data_source_block           1
_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 
;
_cod_original_sg_symbol_H-M      C2/c
_cod_database_code               7051225