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_7157786
_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_sum            'C40 H32'
_chemical_formula_weight         512.65
_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   geom
_audit_creation_method           SHELXL-2014/7
_audit_update_record
;
2020-08-15 deposited with the CCDC.	2020-10-22 downloaded from the CCDC.
;
_cell_angle_alpha                100.338(2)
_cell_angle_beta                 99.001(3)
_cell_angle_gamma                104.084(2)
_cell_formula_units_Z            2
_cell_length_a                   10.4475(5)
_cell_length_b                   12.2806(5)
_cell_length_c                   12.3903(7)
_cell_measurement_reflns_used    2394
_cell_measurement_temperature    296(2)
_cell_measurement_theta_max      21.75
_cell_measurement_theta_min      2.85
_cell_volume                     1483.14(13)
_computing_cell_refinement       'Bruker SAINT'
_computing_data_collection       'Bruker APEX2'
_computing_data_reduction        'Bruker SAINT'
_computing_molecular_graphics    'Bruker SHELXTL'
_computing_publication_material  'Bruker SHELXTL'
_computing_structure_refinement  'SHELXL-2014/7 (Sheldrick, 2014)'
_computing_structure_solution    'SHELXS-97 (Sheldrick 2008)'
_diffrn_ambient_temperature      296(2)
_diffrn_measured_fraction_theta_full 0.994
_diffrn_measured_fraction_theta_max 0.994
_diffrn_measurement_device_type  'Bruker APEX-II CCD'
_diffrn_measurement_method       '\f and \w scans'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0456
_diffrn_reflns_av_unetI/netI     0.0519
_diffrn_reflns_Laue_measured_fraction_full 0.994
_diffrn_reflns_Laue_measured_fraction_max 0.994
_diffrn_reflns_limit_h_max       12
_diffrn_reflns_limit_h_min       -12
_diffrn_reflns_limit_k_max       13
_diffrn_reflns_limit_k_min       -14
_diffrn_reflns_limit_l_max       14
_diffrn_reflns_limit_l_min       -14
_diffrn_reflns_number            19603
_diffrn_reflns_point_group_measured_fraction_full 0.994
_diffrn_reflns_point_group_measured_fraction_max 0.994
_diffrn_reflns_theta_full        24.888
_diffrn_reflns_theta_max         24.888
_diffrn_reflns_theta_min         1.755
_exptl_absorpt_coefficient_mu    0.065
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.148
_exptl_crystal_description       BLock
_exptl_crystal_F_000             544
_exptl_crystal_size_max          0.250
_exptl_crystal_size_mid          0.220
_exptl_crystal_size_min          0.100
_refine_diff_density_max         0.136
_refine_diff_density_min         -0.143
_refine_diff_density_rms         0.032
_refine_ls_extinction_coef       0.0080(14)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     'SHELXL-2014/7 (Sheldrick 2014'
_refine_ls_goodness_of_fit_ref   1.008
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     362
_refine_ls_number_reflns         5144
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.008
_refine_ls_R_factor_all          0.1036
_refine_ls_R_factor_gt           0.0490
_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^)+(0.0521P)^2^+0.1937P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1054
_refine_ls_wR_factor_ref         0.1347
_reflns_Friedel_coverage         0.000
_reflns_number_gt                2908
_reflns_number_total             5144
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d0ob01871f2.cif
_cod_data_source_block           wh1
_cod_database_code               7157786
_shelx_shelxl_version_number     2014/7
_shelx_estimated_absorpt_t_min   0.984
_shelx_estimated_absorpt_t_max   0.994
_shelx_res_checksum              66890