Serendipity: Werner's argument that the `two-only forms' (green and violet) of [CoCl~2~(en)~2~]^+^ salts demanded his octahedral model was correct. True?
Bernal, Ivan; Lalancette, Roger A.; Acta Crystallographica Section C 76 (2020) –; doi:10.1107/S2053229620002272

data_2021992
_publ_section_title
;
 Serendipity: Werner's argument that the `two-only forms' (green and
 violet) of [CoCl~2~(en)~2~]^+^ salts demanded his octahedral model was
 correct. True?
;
_journal_coeditor_code           DG3005
_journal_issue                   3
_journal_name_full               'Acta Crystallographica Section C'
_journal_page_first
;
;
_journal_paper_doi               10.1107/S2053229620002272
_journal_volume                  76
_journal_year                    2020
_chemical_formula_iupac          '[Co Cl2 (C2 H8 N2)2]Cl, 3/2(H2 O)'
_chemical_formula_moiety         'C4 H16 Cl2 Co N4 +, Cl -, 1.5(H2 O)'
_chemical_formula_sum            'C4 H19 Cl3 Co N4 O1.5'
_chemical_formula_weight         312.51
_space_group_crystal_system      triclinic
_space_group_IT_number           2
_space_group_name_Hall           '-P 1'
_space_group_name_H-M_alt        'P -1'
_atom_sites_solution_hydrogens   mixed
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-2014/7
_cell_angle_alpha                105.540(2)
_cell_angle_beta                 94.630(2)
_cell_angle_gamma                108.581(2)
_cell_formula_units_Z            4
_cell_length_a                   8.7163(3)
_cell_length_b                   11.1146(4)
_cell_length_c                   14.0703(5)
_cell_measurement_reflns_used    9124
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      70.03
_cell_measurement_theta_min      3.32
_cell_volume                     1224.06(8)
_computing_cell_refinement
;
APEX2 (Bruker, 2008)
;
_computing_data_collection
;
APEX2 (Bruker, 2008)
;
_computing_data_reduction
;
SAINT (Bruker, 2008)
;
_computing_molecular_graphics
;
SHELXTL (Sheldrick, 2008)
;
_computing_publication_material
;
SHELXTL (Sheldrick, 2008)
;
_computing_structure_refinement
;
SHELXL2014 (Sheldrick, 2015b)
;
_computing_structure_solution
;
SHELXT2014 (Sheldrick, 2015a)
;
_diffrn_ambient_temperature      100(2)
_diffrn_measured_fraction_theta_full 0.929
_diffrn_measured_fraction_theta_max 0.898
_diffrn_measurement_device_type  'Bruker SMART CCD APEXII area-detector'
_diffrn_measurement_method       '\f and \w'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54178
_diffrn_reflns_av_R_equivalents  0.0386
_diffrn_reflns_av_unetI/netI     0.0404
_diffrn_reflns_limit_h_max       10
_diffrn_reflns_limit_h_min       -10
_diffrn_reflns_limit_k_max       13
_diffrn_reflns_limit_k_min       -13
_diffrn_reflns_limit_l_max       17
_diffrn_reflns_limit_l_min       -16
_diffrn_reflns_number            11708
_diffrn_reflns_theta_full        67.679
_diffrn_reflns_theta_max         70.067
_diffrn_reflns_theta_min         3.315
_exptl_absorpt_coefficient_mu    16.875
_exptl_absorpt_correction_T_max  0.5121
_exptl_absorpt_correction_T_min  0.0406
_exptl_absorpt_correction_type   numerical
_exptl_absorpt_process_details
;
(SADABS; Bruker, 2008)
;
_exptl_crystal_colour            purple
_exptl_crystal_density_diffrn    1.696
_exptl_crystal_description       plate
_exptl_crystal_F_000             644
_exptl_crystal_size_max          0.611
_exptl_crystal_size_mid          0.189
_exptl_crystal_size_min          0.065
_refine_diff_density_max         0.625
_refine_diff_density_min         -0.610
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.047
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     262
_refine_ls_number_reflns         4191
_refine_ls_number_restraints     6
_refine_ls_restrained_S_all      1.046
_refine_ls_R_factor_all          0.0432
_refine_ls_R_factor_gt           0.0381
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0460P)^2^+2.4820P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0934
_refine_ls_wR_factor_ref         0.0972
_reflns_number_gt                3864
_reflns_number_total             4191
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            dg3005sup1.cif
_cod_data_source_block           I
_cod_depositor_comments
;

2022-12-20
Z value and formula fixed to values more according to usual
chemical conventions.                 miguel
;
_cod_original_formula_sum            'C8 H38 Cl6 Co2 N8 O3'
_cod_original_formula_weight         625.02
_cod_original_formula_moiety         '2(C4 H16 Cl2 Co N4 +), 2(Cl -), 3(H2 O)'
_cod_original_formula_iupac          '[Co Cl2 (C2 H8 N2)2]2 Cl2, 3H2 O'
_cod_original_formula_units_Z            2
_cod_database_code               2021992
_shelx_estimated_absorpt_t_min   0.034
_shelx_estimated_absorpt_t_max   0.407
_shelx_hkl_checksum              91018
_shelx_res_checksum              66535
_cod_database_fobs_code 2021992