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_4107345
_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_sum            'C40 H89 Nb O3 Si3'
_chemical_formula_weight         795.29
_chemical_name_systematic
; 
 ? 
;
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_cell_angle_beta                 91.034(3)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   13.0005(9)
_cell_length_b                   20.9227(15)
_cell_length_c                   17.2188(11)
_cell_measurement_reflns_used    6902
_cell_measurement_temperature    173(2)
_cell_measurement_theta_max      29.42
_cell_measurement_theta_min      2.28
_cell_volume                     4682.8(6)
_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 0.996
_diffrn_measured_fraction_theta_max 0.996
_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  0.0438
_diffrn_reflns_av_sigmaI/netI    0.0499
_diffrn_reflns_limit_h_max       18
_diffrn_reflns_limit_h_min       -16
_diffrn_reflns_limit_k_max       29
_diffrn_reflns_limit_k_min       -30
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_diffrn_reflns_limit_l_min       -25
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_diffrn_reflns_theta_full        31.29
_diffrn_reflns_theta_max         31.29
_diffrn_reflns_theta_min         1.53
_exptl_absorpt_coefficient_mu    0.365
_exptl_absorpt_correction_T_max  0.9820
_exptl_absorpt_correction_T_min  0.9306
_exptl_absorpt_correction_type   multi-scan
_exptl_crystal_colour            brown
_exptl_crystal_density_diffrn    1.128
_exptl_crystal_density_meas      0
_exptl_crystal_description       plate
_exptl_crystal_F_000             1744
_exptl_crystal_size_max          0.20
_exptl_crystal_size_mid          0.15
_exptl_crystal_size_min          0.05
_refine_diff_density_max         0.662
_refine_diff_density_min         -0.347
_refine_diff_density_rms         0.062
_refine_ls_extinction_method     none
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_refine_ls_matrix_type           full
_refine_ls_number_parameters     491
_refine_ls_number_reflns         15222
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_refine_ls_R_factor_all          0.0653
_refine_ls_R_factor_gt           0.0351
_refine_ls_shift/su_max          0.027
_refine_ls_shift/su_mean         0.002
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0422P)^2^+0.4295P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0849
_refine_ls_wR_factor_ref         0.0935
_reflns_number_gt                10571
_reflns_number_total             15222
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ja074972j-file006.cif
_cod_data_source_block           kh5
_cod_database_code               4107345