Which isomer is it, 1,2,5,6- or 1,4,5,8-tetrasubstituted cycloocta-1,3,5,7-tetraene? Synthesis of symmetrically tetrasubstituted cycloocta-1,3,5,7-tetraene derivatives
Gadigennavar, Savita; Ranganathan, Madhav; Sankararaman, Sethuraman; Organic & Biomolecular Chemistry 18 (2020) 9284–9291; doi:10.1039/D0OB01871F

data_7157787
_publ_section_title
;
 Which isomer is it, 1,2,5,6- or 1,4,5,8-tetrasubstituted
 cycloocta-1,3,5,7-tetraene? Synthesis of symmetrically tetrasubstituted
 cycloocta-1,3,5,7-tetraene derivatives
;
_journal_issue                   45
_journal_name_full               'Organic &amp; Biomolecular Chemistry'
_journal_page_first              9284
_journal_page_last               9291
_journal_paper_doi               10.1039/D0OB01871F
_journal_volume                  18
_journal_year                    2020
_chemical_formula_moiety         'C12 H12 Br4'
_chemical_formula_sum            'C12 H12 Br4'
_chemical_formula_weight         475.86
_space_group_crystal_system      monoclinic
_space_group_IT_number           14
_space_group_name_Hall           '-P 2ybc'
_space_group_name_H-M_alt        'P 1 21/c 1'
_atom_sites_solution_hydrogens   geom
_audit_creation_method           SHELXL-2018/3
_audit_update_record
;
2020-08-29 deposited with the CCDC.	2020-10-22 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 94.823(3)
_cell_angle_gamma                90
_cell_formula_units_Z            12
_cell_length_a                   14.8169(9)
_cell_length_b                   23.1350(15)
_cell_length_c                   13.2408(7)
_cell_measurement_reflns_used    4613
_cell_measurement_temperature    296(2)
_cell_measurement_theta_max      19.70
_cell_measurement_theta_min      2.76
_cell_volume                     4522.7(5)
_computing_cell_refinement       'Bruker SAINT'
_computing_data_collection       'Bruker APEX2'
_computing_data_reduction        'Bruker SAINT'
_computing_structure_refinement  'SHELXL-2018/3 (Sheldrick, 2018)'
_computing_structure_solution    'SHELXT 2018/2 (Sheldrick, 2018)'
_diffrn_ambient_temperature      296(2)
_diffrn_measured_fraction_theta_full 0.989
_diffrn_measured_fraction_theta_max 0.989
_diffrn_measurement_device_type  'Bruker apex 2'
_diffrn_measurement_method       '\w and \f scan'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.1794
_diffrn_reflns_av_unetI/netI     0.1802
_diffrn_reflns_Laue_measured_fraction_full 0.989
_diffrn_reflns_Laue_measured_fraction_max 0.989
_diffrn_reflns_limit_h_max       17
_diffrn_reflns_limit_h_min       -17
_diffrn_reflns_limit_k_max       27
_diffrn_reflns_limit_k_min       -27
_diffrn_reflns_limit_l_max       14
_diffrn_reflns_limit_l_min       -15
_diffrn_reflns_number            43078
_diffrn_reflns_point_group_measured_fraction_full 0.989
_diffrn_reflns_point_group_measured_fraction_max 0.989
_diffrn_reflns_theta_full        24.999
_diffrn_reflns_theta_max         24.999
_diffrn_reflns_theta_min         1.379
_diffrn_source                   'fine focus sealed tube'
_exptl_absorpt_coefficient_mu    10.652
_exptl_absorpt_correction_T_max  0.7453
_exptl_absorpt_correction_T_min  0.3443
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'SADABS (Bruker)'
_exptl_crystal_colour            brown
_exptl_crystal_density_diffrn    2.097
_exptl_crystal_description       Block
_exptl_crystal_F_000             2688
_exptl_crystal_size_max          0.250
_exptl_crystal_size_mid          0.220
_exptl_crystal_size_min          0.100
_refine_diff_density_max         1.784
_refine_diff_density_min         -1.237
_refine_diff_density_rms         0.177
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.022
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     433
_refine_ls_number_reflns         7895
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.022
_refine_ls_R_factor_all          0.2130
_refine_ls_R_factor_gt           0.0739
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.1037P)^2^+2.9041P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1762
_refine_ls_wR_factor_ref         0.2393
_reflns_Friedel_coverage         0.000
_reflns_number_gt                3286
_reflns_number_total             7895
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d0ob01871f2.cif
_cod_data_source_block           shelx
_cod_original_sg_symbol_H-M      'P 21/c'
_cod_database_code               7157787
_shelx_shelxl_version_number     2018/3
_shelx_estimated_absorpt_t_min   0.176
_shelx_estimated_absorpt_t_max   0.416
_shelx_res_checksum              48618