A Theoretical and Experimental Scale of Aromaticity. The First Nucleus-Independent Chemical Shifts (NICS) Study of the Dimethyldihydropyrene Nucleus
Richard Vaughan Williams; John R. Armantrout; Brendan Twamley; Reginald H. Mitchell; Timothy R. Ward; Subhajit Bandyopadhyay; Journal of the American Chemical Society 124 (2002) 13495–13505; doi:10.1021/ja020595t

data_4115265
_publ_section_title
;
 A Theoretical and Experimental Scale of Aromaticity. The First
 Nucleus-Independent Chemical Shifts (NICS) Study of the
 Dimethyldihydropyrene Nucleus
;
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              13495
_journal_page_last               13505
_journal_paper_doi               10.1021/ja020595t
_journal_volume                  124
_journal_year                    2002
_chemical_formula_sum            'C26 H32'
_chemical_formula_weight         344.52
_chemical_name_common            Bis(tBu)dihydrodimethylpyrene
_space_group_IT_number           15
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-C 2yc'
_symmetry_space_group_name_H-M   'C 1 2/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                 91.02(2)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   14.3791(11)
_cell_length_b                   11.7604(9)
_cell_length_c                   11.7230(9)
_cell_measurement_reflns_used    784
_cell_measurement_temperature    203(2)
_cell_measurement_theta_max      27.76
_cell_measurement_theta_min      2.23
_cell_volume                     1982.1(3)
_computing_cell_refinement       'Bruker SAINTPlus v. 6.02'
_computing_data_collection       'Bruker SMART'
_computing_data_reduction        'Bruker SAINTPlus v. 6.02'
_computing_molecular_graphics    'XP, Bruker SHELXTL v. 5.10'
_computing_publication_material  'XCIF, Bruker SHELXTL v. 5.10'
_computing_structure_refinement  'XL, Bruker SHELXTL v. 5.10'
_computing_structure_solution    'XS, Bruker SHELXTL v. 5.10'
_diffrn_ambient_temperature      203(2)
_diffrn_detector_area_resol_mean 8.3
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.999
_diffrn_measurement_device_type  'Siemens/Bruker SMART 1K'
_diffrn_measurement_method       \w
_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  0.0326
_diffrn_reflns_av_sigmaI/netI    0.0320
_diffrn_reflns_limit_h_max       16
_diffrn_reflns_limit_h_min       -17
_diffrn_reflns_limit_k_max       13
_diffrn_reflns_limit_k_min       -13
_diffrn_reflns_limit_l_max       13
_diffrn_reflns_limit_l_min       -13
_diffrn_reflns_number            7290
_diffrn_reflns_theta_full        25.00
_diffrn_reflns_theta_max         25.00
_diffrn_reflns_theta_min         2.24
_diffrn_standards_decay_%        <0.01
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.064
_exptl_absorpt_correction_T_max  0.9961
_exptl_absorpt_correction_T_min  0.9835
_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details   'SADABS (Sheldrick, 1999)'
_exptl_crystal_colour            green
_exptl_crystal_density_diffrn    1.155
_exptl_crystal_description       needle
_exptl_crystal_F_000             752
_exptl_crystal_size_max          0.26
_exptl_crystal_size_mid          0.10
_exptl_crystal_size_min          0.06
_refine_diff_density_max         0.205
_refine_diff_density_min         -0.162
_refine_diff_density_rms         0.034
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.016
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     122
_refine_ls_number_reflns         1738
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.016
_refine_ls_R_factor_all          0.0637
_refine_ls_R_factor_gt           0.0419
_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^)+(0.0550P)^2^+0.8764P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1007
_refine_ls_wR_factor_ref         0.1124
_reflns_number_gt                1301
_reflns_number_total             1738
_reflns_threshold_expression     I>2sigma(I)
_cod_data_source_file            ja020595t_1.cif
_cod_data_source_block           3
_cod_database_code               4115265