Syntheses and Crystal Structures of Fused Thiophenes: [7]Helicene and Double Helicene, a D2-Symmetric Dimer of 3,3'-Bis(dithieno[2,3-b:3',2'-d]thiophene)
Chunli Li; Jianwu Shi; Li Xu; Yangguang Wang; Yanxiang Cheng; Hua Wang; Journal of Organic Chemistry 74 (2009) 408–411; doi:10.1021/jo802080g

data_4024241
_publ_section_title
;
Syntheses and Crystal Structures of Fused Thiophenes: [7]Helicene and
Double Helicene, a D2-Symmetric Dimer of
3,3'-Bis(dithieno[2,3-b:3',2'-d]thiophene)
;
_journal_name_full               'Journal of Organic Chemistry'
_journal_page_first              408
_journal_page_last               411
_journal_paper_doi               10.1021/jo802080g
_journal_volume                  74
_journal_year                    2009
_chemical_formula_sum            'C22 H22 S6 Si2'
_chemical_formula_weight         534.94
_space_group_IT_number           33
_symmetry_space_group_name_Hall  'P 2c -2n'
_symmetry_space_group_name_H-M   'P n a 21'
_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                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   11.4964(16)
_cell_length_b                   14.345(2)
_cell_length_c                   15.846(2)
_cell_measurement_temperature    296(2)
_cell_volume                     2613.3(7)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      296(2)
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_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  0.0352
_diffrn_reflns_av_sigmaI/netI    0.0436
_diffrn_reflns_limit_h_max       14
_diffrn_reflns_limit_h_min       -11
_diffrn_reflns_limit_k_max       17
_diffrn_reflns_limit_k_min       -15
_diffrn_reflns_limit_l_max       19
_diffrn_reflns_limit_l_min       -19
_diffrn_reflns_number            13842
_diffrn_reflns_theta_full        25.99
_diffrn_reflns_theta_max         25.99
_diffrn_reflns_theta_min         1.91
_exptl_absorpt_coefficient_mu    0.624
_exptl_crystal_density_diffrn    1.360
_exptl_crystal_density_method    'not measured'
_exptl_crystal_F_000             1112
_refine_diff_density_max         0.199
_refine_diff_density_min         -0.205
_refine_diff_density_rms         0.039
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.72(7)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.987
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     279
_refine_ls_number_reflns         4954
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      0.987
_refine_ls_R_factor_all          0.0437
_refine_ls_R_factor_gt           0.0339
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0415P)^2^+0.3342P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0785
_refine_ls_wR_factor_ref         0.0834
_reflns_number_gt                4264
_reflns_number_total             4954
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            jo802080g_si_003.cif
_cod_data_source_block           test_0m
_cod_database_code               4024241