Kinetically Blocked Stable Heptazethrene and Octazethrene: Closed-Shell or Open-Shell in the Ground State?
Yuan Li; Wee-Kuan Heng; Byung Sun Lee; Naoki Aratani; José L. Zafra; Nina Bao; Richmond Lee; Young Mo Sung; Zhe Sun; Kuo-Wei Huang; Richard D. Webster; Juan T. López Navarrete; Dongho Kim; Atsuhiro Osuka; Juan Casado; Jun Ding; Jishan Wu; Journal of the American Chemical Society 134 (2012) 14913–14922; doi:10.1021/ja304618v

data_4118586
_publ_section_title
;
 Kinetically Blocked Stable Heptazethrene and Octazethrene: Closed-Shell
 or Open-Shell in the Ground State?
;
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              14913
_journal_page_last               14922
_journal_paper_doi               10.1021/ja304618v
_journal_volume                  134
_journal_year                    2012
_chemical_formula_moiety         'C52 H60 Si2'
_chemical_formula_sum            'C52 H60 Si2'
_chemical_formula_weight         741.18
_chemical_name_systematic
; 
 ? 
;
_space_group_IT_number           15
_symmetry_cell_setting           monoclinic
_symmetry_Int_Tables_number      15
_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                 122.838(4)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   18.548(6)
_cell_length_b                   19.178(6)
_cell_length_c                   13.920(5)
_cell_measurement_reflns_used    4449
_cell_measurement_temperature    90
_cell_measurement_theta_max      28.30
_cell_measurement_theta_min      2.61
_cell_volume                     4160(2)
_computing_cell_refinement       'APEX2 (Bruker AXS, 2006)'
_computing_data_collection       'APEX2 '
_computing_data_reduction        'SAINT (Bruker AXS, 2004)'
_computing_molecular_graphics    'XSHEL (Bruker AXS,2002)'
_computing_publication_material  'XCIF (Bruker AXS, 2001)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      90
_diffrn_detector_area_resol_mean 8.333
_diffrn_measured_fraction_theta_full 0.997
_diffrn_measured_fraction_theta_max 0.997
_diffrn_measurement_device_type  'Bruker APEXII CCD area detector'
_diffrn_measurement_method       'phi and omega scans'
_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  0.0198
_diffrn_reflns_av_sigmaI/netI    0.0269
_diffrn_reflns_limit_h_max       17
_diffrn_reflns_limit_h_min       -23
_diffrn_reflns_limit_k_max       24
_diffrn_reflns_limit_k_min       -24
_diffrn_reflns_limit_l_max       17
_diffrn_reflns_limit_l_min       -13
_diffrn_reflns_number            11482
_diffrn_reflns_theta_full        27.00
_diffrn_reflns_theta_max         27.00
_diffrn_reflns_theta_min         2.12
_exptl_absorpt_coefficient_mu    0.121
_exptl_absorpt_correction_T_max  0.9880
_exptl_absorpt_correction_T_min  0.9763
_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details
;
SADABS Sheldrick 1996
;
_exptl_crystal_colour            blue
_exptl_crystal_density_diffrn    1.183
_exptl_crystal_description       prism
_exptl_crystal_F_000             1600
_exptl_crystal_size_max          0.20
_exptl_crystal_size_mid          0.10
_exptl_crystal_size_min          0.10
_refine_diff_density_max         0.560
_refine_diff_density_min         -0.272
_refine_diff_density_rms         0.056
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.039
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     251
_refine_ls_number_reflns         4539
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.039
_refine_ls_R_factor_all          0.0609
_refine_ls_R_factor_gt           0.0480
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0768P)^2^+4.4061P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1300
_refine_ls_wR_factor_ref         0.1398
_reflns_number_gt                3696
_reflns_number_total             4539
_reflns_threshold_expression     >2sigma
_cod_data_source_file            ja304618v_si_002.cif
_cod_data_source_block           20407wu_0m
_cod_original_sg_symbol_H-M      'C 1 2/c 1 '
_cod_database_code               4118586