Dimethylcalcium.
Wolf, Benjamin M.; Stuhl, Christoph; Maichle-Mössmer, Cäcilia; Anwander, Reiner; Journal of the American Chemical Society 140 (2018) 2373–2383; doi:10.1021/jacs.7b12984

data_4131913
_publ_section_title
;
 Dimethylcalcium.
;
_journal_issue                   6
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              2373
_journal_page_last               2383
_journal_paper_doi               10.1021/jacs.7b12984
_journal_volume                  140
_journal_year                    2018
_chemical_formula_sum            'C26 H54 Ca2 I2 O6'
_chemical_formula_weight         796.65
_space_group_crystal_system      orthorhombic
_space_group_IT_number           33
_space_group_name_Hall           'P 2c -2n'
_space_group_name_H-M_alt        'P n a 21'
_atom_sites_solution_hydrogens   geom
_audit_creation_method           SHELXL-2014/7
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   19.866(3)
_cell_length_b                   7.7093(11)
_cell_length_c                   22.122(3)
_cell_measurement_reflns_used    503
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      26.52
_cell_measurement_theta_min      2.264
_cell_volume                     3388.0(8)
_computing_cell_refinement       'SAINT V8.37A (Bruker AXS Inc., 2015)'
_computing_data_collection       'APEX3 v2016.5-0 (Bruker AXS)'
_computing_data_reduction        'SAINT V8.37A (Bruker AXS Inc., 2015)'
_computing_structure_refinement  'SHELXL-2014/7 (Sheldrick, 2014)'
_computing_structure_solution
'XT, VERSION 2014/5,SHELXS-13 (Sheldrick 2008)'
_diffrn_ambient_temperature      100(2)
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.998
_diffrn_measurement_device_type  'Bruker APEX II DUO'
_diffrn_measurement_method       'omega scans'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0553
_diffrn_reflns_av_unetI/netI     0.0613
_diffrn_reflns_Laue_measured_fraction_full 0.998
_diffrn_reflns_Laue_measured_fraction_max 0.998
_diffrn_reflns_limit_h_max       28
_diffrn_reflns_limit_h_min       -21
_diffrn_reflns_limit_k_max       11
_diffrn_reflns_limit_k_min       -10
_diffrn_reflns_limit_l_max       31
_diffrn_reflns_limit_l_min       -31
_diffrn_reflns_number            35354
_diffrn_reflns_point_group_measured_fraction_full 0.999
_diffrn_reflns_point_group_measured_fraction_max 0.998
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         30.447
_diffrn_reflns_theta_min         2.050
_diffrn_source                   'ImuS-focus sealed tube'
_exptl_absorpt_coefficient_mu    2.192
_exptl_absorpt_correction_T_max  0.7461
_exptl_absorpt_correction_T_min  0.6370
_exptl_absorpt_correction_type   numerical
_exptl_absorpt_process_details   sadabs
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.562
_exptl_crystal_description       column
_exptl_crystal_F_000             1616
_exptl_crystal_size_max          0.426
_exptl_crystal_size_mid          0.144
_exptl_crystal_size_min          0.118
_refine_diff_density_max         1.849
_refine_diff_density_min         -2.570
_refine_diff_density_rms         0.186
_refine_ls_abs_structure_details
;
 Refined as an inversion twin.
;
_refine_ls_abs_structure_Flack   0.47(6)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.085
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     640
_refine_ls_number_reflns         9799
_refine_ls_number_restraints     2785
_refine_ls_restrained_S_all      1.006
_refine_ls_R_factor_all          0.0802
_refine_ls_R_factor_gt           0.0689
_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^)+(0.0245P)^2^+38.0550P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1414
_refine_ls_wR_factor_ref         0.1461
_reflns_Friedel_coverage         0.954
_reflns_Friedel_fraction_full    0.999
_reflns_Friedel_fraction_max     0.998
_reflns_number_gt                8561
_reflns_number_total             9799
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            ja7b12984_si_002.cif
_cod_data_source_block           3a_mo_bw393_200_0ma_Cili
_cod_original_cell_volume        3388.1(8)
_cod_database_code               4131913
_shelx_shelxl_version_number     2014/7
_shelx_estimated_absorpt_t_min   0.455
_shelx_estimated_absorpt_t_max   0.782
_shelx_res_checksum              42626
_shelx_hkl_checksum              15172