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_4114371
_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 H8 Cl6 S6'
_chemical_formula_weight         701.36
_space_group_IT_number           14
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-P 2ybc'
_symmetry_space_group_name_H-M   'P 1 21/c 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                 103.298(2)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   11.5178(9)
_cell_length_b                   21.9995(18)
_cell_length_c                   11.0513(9)
_cell_measurement_temperature    218(2)
_cell_volume                     2725.2(4)
_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  0.0216
_diffrn_reflns_av_sigmaI/netI    0.0206
_diffrn_reflns_limit_h_max       15
_diffrn_reflns_limit_h_min       -14
_diffrn_reflns_limit_k_max       21
_diffrn_reflns_limit_k_min       -29
_diffrn_reflns_limit_l_max       14
_diffrn_reflns_limit_l_min       -13
_diffrn_reflns_number            20017
_diffrn_reflns_theta_full        28.28
_diffrn_reflns_theta_max         28.28
_diffrn_reflns_theta_min         1.82
_exptl_absorpt_coefficient_mu    1.107
_exptl_absorpt_correction_T_max  0.6721
_exptl_absorpt_correction_T_min  0.6076
_exptl_absorpt_correction_type   SADABS
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.709
_exptl_crystal_density_meas      0
_exptl_crystal_description       'prism frag.'
_exptl_crystal_F_000             1400
_exptl_crystal_size_max          0.50
_exptl_crystal_size_mid          0.42
_exptl_crystal_size_min          0.39
_refine_diff_density_max         0.544
_refine_diff_density_min         -0.390
_refine_diff_density_rms         0.069
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.029
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     333
_refine_ls_number_reflns         6757
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.029
_refine_ls_R_factor_all          0.0360
_refine_ls_R_factor_gt           0.0311
_refine_ls_shift/su_max          0.002
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0455P)^2^+1.4045P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0805
_refine_ls_wR_factor_ref         0.0853
_reflns_number_gt                5968
_reflns_number_total             6757
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ja038260esi20031011_090515_1.cif
_cod_data_source_block           1a
_cod_database_code               4114371