Access to a Stable Si2N2 Four-Membered Ring with Non-Kekulé Singlet Biradical Character from a Disilyne
Katsuhiko Takeuchi; Masaaki Ichinohe; Akira Sekiguchi; Journal of the American Chemical Society 133 (2011) 12478–12481; doi:10.1021/ja2059846

data_4106592
_publ_section_title
;
 Access to a Stable Si2N2 Four-Membered Ring with Non-Kekul\'e Singlet
 Biradical Character from a Disilyne
;
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              12478
_journal_page_last               12481
_journal_paper_doi               10.1021/ja2059846
_journal_volume                  133
_journal_year                    2011
_chemical_formula_sum            'C54 H116 N2 O Si12'
_chemical_formula_weight         1146.57
_chemical_name_systematic
; 
 2,4-Bis{bis[bis(trimethylsilyl)methyl]isopropylsilyl}
-1,3-bis(3,5-dimethylphenyl)-1,3-diaza-2,4-disilacyclobutane-2,4-diyl 
;
_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                 93.3760(10)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   33.068(3)
_cell_length_b                   17.4569(17)
_cell_length_c                   11.9688(11)
_cell_measurement_reflns_used    9794
_cell_measurement_temperature    150.0(1)
_cell_measurement_theta_max      28.16
_cell_measurement_theta_min      2.18
_cell_volume                     6897.2(11)
_computing_cell_refinement       'Bruker SAINT'
_computing_data_collection       'Bruker APEX2'
_computing_data_reduction        'Bruker SAINT'
_computing_molecular_graphics    'Bruker SHELXTL'
_computing_publication_material  'Bruker SHELXTL'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 2008)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      150.0(1)
_diffrn_detector_area_resol_mean 8.333
_diffrn_measured_fraction_theta_full 0.993
_diffrn_measured_fraction_theta_max 0.993
_diffrn_measurement_device_type  'Bruker APEX-II CCD'
_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  0.0205
_diffrn_reflns_av_sigmaI/netI    0.0154
_diffrn_reflns_limit_h_max       42
_diffrn_reflns_limit_h_min       -42
_diffrn_reflns_limit_k_max       22
_diffrn_reflns_limit_k_min       -22
_diffrn_reflns_limit_l_max       15
_diffrn_reflns_limit_l_min       -15
_diffrn_reflns_number            38455
_diffrn_reflns_theta_full        27.48
_diffrn_reflns_theta_max         27.48
_diffrn_reflns_theta_min         1.23
_exptl_absorpt_coefficient_mu    0.260
_exptl_absorpt_correction_T_max  0.9513
_exptl_absorpt_correction_T_min  0.8831
_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details
;
SADABS Sheldrick 1996
;
_exptl_crystal_colour            Purple
_exptl_crystal_density_diffrn    1.104
_exptl_crystal_description       cubic
_exptl_crystal_F_000             2520
_exptl_crystal_size_max          0.49
_exptl_crystal_size_mid          0.29
_exptl_crystal_size_min          0.19
_refine_diff_density_max         0.837
_refine_diff_density_min         -0.828
_refine_diff_density_rms         0.062
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.032
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     312
_refine_ls_number_reflns         7887
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.032
_refine_ls_R_factor_all          0.0444
_refine_ls_R_factor_gt           0.0394
_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^)+(0.0631P)^2^+11.0753P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1139
_refine_ls_wR_factor_ref         0.1193
_reflns_number_gt                7057
_reflns_number_total             7887
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ja2059846_si_001.cif
_cod_data_source_block           si2n2thf_0m
_cod_original_sg_symbol_H-M      'C 1 2/c 1 '
_cod_database_code               4106592