Experimental and theoretical electron density study of a highly twisted polycyclic aromatic hydrocarbon: 4-methyl-[4]helicene.
Wolstenholme, David J.; Matta, Chérif F; Cameron, T. Stanley; The journal of physical chemistry. A 111 (2007) 8803–8813; doi:10.1021/jp071002+

data_1516636
_publ_section_title
;
 Experimental and theoretical electron density study of a highly twisted
 polycyclic aromatic hydrocarbon: 4-methyl-[4]helicene.
;
_journal_issue                   36
_journal_name_full               'The journal of physical chemistry. A'
_journal_page_first              8803
_journal_page_last               8813
_journal_paper_doi               10.1021/jp071002+
_journal_volume                  111
_journal_year                    2007
_chemical_formula_moiety         'C19 H14'
_chemical_formula_sum            'C19 H14'
_chemical_formula_weight         242.30
_chemical_name_common            4-methylbenzo[c]phenanthrene
_space_group_IT_number           14
_symmetry_space_group_name_Hall  '-P 2ybc'
_symmetry_space_group_name_H-M   'P 1 21/c 1'
_audit_conform_dict_location     ftp://ftp.iucr.org/pub/cif_core.dic
_audit_conform_dict_name         cif_core.dic
_audit_conform_dict_version      2.3
_audit_creation_date             '28-Mar-03 T11:27:19-00:00'
_audit_creation_method           'XD routine XDCIF'
_cell_angle_alpha                90.00
_cell_angle_beta                 92.772(3)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   7.5875(5)
_cell_length_b                   11.1085(5)
_cell_length_c                   14.9042(9)
_cell_measurement_reflns_used    6667
_cell_measurement_temperature    123.1(5)
_cell_measurement_theta_max      72.2077
_cell_measurement_theta_min      4.1687
_cell_volume                     1254.74(13)
_computing_cell_refinement       'CrystalClear (Rigaku Corp., 2000)'
_computing_data_collection       'CrystalClear (Rigaku Corp., 2000)'
_computing_data_reduction        'CrystalClear (Rigaku Corp., 2000)'
_computing_molecular_graphics    'Volkov et al, (2006)'
_computing_publication_material  'Volkov et al, (2006)'
_computing_structure_refinement  'Volkov et al, (2006)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      123.1(5)
_diffrn_measurement_device_type  ' Rigaku RAPID '
_diffrn_measurement_method       \w
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71070
_diffrn_reflns_limit_h_max       19
_diffrn_reflns_limit_h_min       -11
_diffrn_reflns_limit_k_max       29
_diffrn_reflns_limit_k_min       -22
_diffrn_reflns_limit_l_max       33
_diffrn_reflns_limit_l_min       -39
_diffrn_reflns_number            20461
_diffrn_reflns_theta_max         72.2077
_diffrn_reflns_theta_min         4.1687
_exptl_absorpt_coefficient_mu    0.073
_exptl_absorpt_correction_T_max  0.9856
_exptl_absorpt_correction_T_min  0.9856
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
    Higashi, T. (1995). Program for Absorption Correction.
    Rigaku Corporation, Tokyo, Japan.
;
_exptl_crystal_colour            Colorless
_exptl_crystal_density_diffrn    1.291
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       Prism
_exptl_crystal_F_000             512
_exptl_crystal_size_max          0.18
_exptl_crystal_size_mid          0.19
_exptl_crystal_size_min          0.27
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   2.087
_refine_ls_matrix_type           full
_refine_ls_number_parameters     172
_refine_ls_number_reflns         6861
_refine_ls_number_restraints     0
_refine_ls_R_factor_all          0.104
_refine_ls_R_factor_gt           0.038
_refine_ls_shift/su_max          0
_refine_ls_structure_factor_coef F
_refine_ls_weighting_details
;
        calc w1 = 1/[s^2^(Fo)]
;
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_ref         0.043
_reflns_threshold_expression     >3sigma(I)
_cod_data_source_file            jp071002%2Bsi20070612_041133.cif
_cod_data_source_block           heli
_cod_original_cell_volume        1246.4(3)
_cod_database_code               1516636