Olefin Substitution in (silox)3M(olefin) (silox =tBu3SiO; M = Nb, Ta): The Role of Density of States in Second vs Third Row Transition Metal Reactivity
Kurt F. Hirsekorn; Elliott B. Hulley; Peter T. Wolczanski; Thomas R. Cundari; Journal of the American Chemical Society 130 (2008) 1183–1196; doi:10.1021/ja074972j

data_4107343
_publ_section_title
;
 Olefin Substitution in (silox)3M(olefin) (silox =tBu3SiO; M = Nb, Ta):
 The Role of Density of States in Second vs Third Row Transition Metal
 Reactivity
;
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              1183
_journal_page_last               1196
_journal_paper_doi               10.1021/ja074972j
_journal_volume                  130
_journal_year                    2008
_chemical_formula_moiety         'C38 H85 O3 Si3 Ta'
_chemical_formula_sum            'C80 H180 O7 Si6 Ta2'
_chemical_formula_weight         1784.68
_chemical_name_systematic
; 
 ? 
;
_space_group_IT_number           7
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  'P -2yc'
_symmetry_space_group_name_H-M   'P 1 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                 111.970(3)
_cell_angle_gamma                90.00
_cell_formula_units_Z            2
_cell_length_a                   24.2852(13)
_cell_length_b                   8.8145(5)
_cell_length_c                   23.9509(13)
_cell_measurement_reflns_used    7818
_cell_measurement_temperature    173(2)
_cell_measurement_theta_max      30.67
_cell_measurement_theta_min      2.33
_cell_volume                     4754.7(5)
_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, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      173(2)
_diffrn_measured_fraction_theta_full 0.944
_diffrn_measured_fraction_theta_max 0.944
_diffrn_measurement_device_type  'Bruker X8 APEX II diffractometer'
_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  0.0316
_diffrn_reflns_av_sigmaI/netI    0.0544
_diffrn_reflns_limit_h_max       37
_diffrn_reflns_limit_h_min       -33
_diffrn_reflns_limit_k_max       13
_diffrn_reflns_limit_k_min       -14
_diffrn_reflns_limit_l_max       37
_diffrn_reflns_limit_l_min       -38
_diffrn_reflns_number            79419
_diffrn_reflns_theta_full        35.28
_diffrn_reflns_theta_max         35.28
_diffrn_reflns_theta_min         1.71
_exptl_absorpt_coefficient_mu    2.420
_exptl_absorpt_correction_T_max  0.8886
_exptl_absorpt_correction_T_min  0.5830
_exptl_absorpt_correction_type   multi-scan
_exptl_crystal_colour            yellow
_exptl_crystal_density_diffrn    1.247
_exptl_crystal_density_meas      0
_exptl_crystal_description       plate
_exptl_crystal_F_000             1892
_exptl_crystal_size_max          0.25
_exptl_crystal_size_mid          0.20
_exptl_crystal_size_min          0.05
_refine_diff_density_max         1.271
_refine_diff_density_min         -0.833
_refine_diff_density_rms         0.098
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.503(3)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.015
_refine_ls_hydrogen_treatment    riding
_refine_ls_matrix_type           full
_refine_ls_number_parameters     886
_refine_ls_number_reflns         35142
_refine_ls_number_restraints     24
_refine_ls_restrained_S_all      1.015
_refine_ls_R_factor_all          0.0484
_refine_ls_R_factor_gt           0.0312
_refine_ls_shift/su_max          2.035
_refine_ls_shift/su_mean         0.141
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0254P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0616
_refine_ls_wR_factor_ref         0.0651
_reflns_number_gt                27820
_reflns_number_total             35142
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ja074972j-file002.cif
_cod_data_source_block           kh7
_cod_original_sg_symbol_H-M      'P 1 2/c 1'
_cod_database_code               4107343