Helical Sexithiophenes: An Experimental and Theoretical Study Implicating the Alternating 2,2':3,3' Regioisomer as a Reliable Helical Motif
Michael J. Marsella; Kunsang Yoon; Adah Almutairi; Sheraz K. Butt; Fook S. Tham; Journal of the American Chemical Society 125 (2003) 13928–13929; doi:10.1021/ja038260e

data_4114373
_publ_section_title
;
 Helical Sexithiophenes: An Experimental and Theoretical Study Implicating
 the Alternating 2,2':3,3' Regioisomer as a Reliable Helical Motif
;
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              13928
_journal_page_last               13929
_journal_paper_doi               10.1021/ja038260e
_journal_volume                  125
_journal_year                    2003
_chemical_formula_sum            'C24 H6 Br2 Cl6 S6'
_chemical_formula_weight         859.17
_space_group_IT_number           14
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-P 2yn'
_symmetry_space_group_name_H-M   'P 1 21/n 1'
_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                 109.939(6)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   10.880(3)
_cell_length_b                   19.026(5)
_cell_length_c                   15.552(4)
_cell_measurement_temperature    218(2)
_cell_volume                     3026.3(14)
_computing_cell_refinement       'Bruker SMART'
_computing_data_collection       'Bruker SMART'
_computing_data_reduction        'Bruker SAINT'
_computing_molecular_graphics    'Bruker SHELXTL'
_computing_publication_material  'Bruker SHELXTL'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      218(2)
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.999
_diffrn_measurement_device_type  'CCD area detector'
_diffrn_measurement_method       'phi and omega scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'Normal-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0453
_diffrn_reflns_av_sigmaI/netI    0.0475
_diffrn_reflns_limit_h_max       13
_diffrn_reflns_limit_h_min       -13
_diffrn_reflns_limit_k_max       21
_diffrn_reflns_limit_k_min       -23
_diffrn_reflns_limit_l_max       19
_diffrn_reflns_limit_l_min       -19
_diffrn_reflns_number            21858
_diffrn_reflns_theta_full        26.37
_diffrn_reflns_theta_max         26.37
_diffrn_reflns_theta_min         1.76
_exptl_absorpt_coefficient_mu    3.640
_exptl_absorpt_correction_T_max  0.5766
_exptl_absorpt_correction_T_min  0.2740
_exptl_absorpt_correction_type   SADABS
_exptl_crystal_colour            'light yellow'
_exptl_crystal_density_diffrn    1.886
_exptl_crystal_density_meas      0
_exptl_crystal_description       'prism frag'
_exptl_crystal_F_000             1672
_exptl_crystal_size_max          0.48
_exptl_crystal_size_mid          0.35
_exptl_crystal_size_min          0.17
_refine_diff_density_max         1.285
_refine_diff_density_min         -0.568
_refine_diff_density_rms         0.126
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.045
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     349
_refine_ls_number_reflns         6190
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.045
_refine_ls_R_factor_all          0.0749
_refine_ls_R_factor_gt           0.0509
_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^)+(0.0733P)^2^+4.4456P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1280
_refine_ls_wR_factor_ref         0.1412
_reflns_number_gt                4563
_reflns_number_total             6190
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ja038260esi20031011_090515_3.cif
_cod_data_source_block           1c
_cod_original_cell_volume        3026.4(14)
_cod_database_code               4114373