Synthesis, Characterization, and Reactions of Isolable (β-Diketiminato)Nb(III) Imido Complexes.
Tomson, Neil C.; Arnold, John; Bergman, Robert G.; Organometallics 29 (2010) 5010–5025; doi:10.1021/om1002528

data_4066021
_publ_section_title
;
 Synthesis, Characterization, and Reactions of Isolable
 (\b-Diketiminato)Nb(III) Imido Complexes.
;
_journal_issue                   21
_journal_name_full               Organometallics
_journal_page_first              5010
_journal_page_last               5025
_journal_paper_doi               10.1021/om1002528
_journal_volume                  29
_journal_year                    2010
_chemical_formula_moiety         'C38 H55 N4 Nb'
_chemical_formula_sum            'C38 H55 N4 Nb'
_chemical_formula_weight         660.77
_chemical_name_systematic
; 
 ? 
;
_space_group_IT_number           19
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  'P 2ac 2ab'
_symmetry_space_group_name_H-M   'P 21 21 21'
_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                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   10.847(17)
_cell_length_b                   17.61(4)
_cell_length_c                   21.45(4)
_cell_measurement_reflns_used    4449
_cell_measurement_temperature    107(2)
_cell_measurement_theta_max      42.546
_cell_measurement_theta_min      6.868
_cell_volume                     4097(14)
_computing_cell_refinement       'Bruker SAINT v7.07'
_computing_data_collection       'Bruker SMART v5.631'
_computing_data_reduction        'Bruker SAINT v7.07'
_computing_molecular_graphics    'Bruker-AXS XP v.6'
_computing_publication_material  'Bruker-AXS XP v.6'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 2008)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 2008)'
_diffrn_ambient_temperature      107(2)
_diffrn_measured_fraction_theta_full 0.945
_diffrn_measured_fraction_theta_max 0.945
_diffrn_measurement_device_type  'SMART 1000'
_diffrn_measurement_method       '\w 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  0.0730
_diffrn_reflns_av_sigmaI/netI    0.1102
_diffrn_reflns_limit_h_max       12
_diffrn_reflns_limit_h_min       -12
_diffrn_reflns_limit_k_max       20
_diffrn_reflns_limit_k_min       -20
_diffrn_reflns_limit_l_max       24
_diffrn_reflns_limit_l_min       -23
_diffrn_reflns_number            20155
_diffrn_reflns_theta_full        25.15
_diffrn_reflns_theta_max         25.15
_diffrn_reflns_theta_min         3.41
_exptl_absorpt_coefficient_mu    0.320
_exptl_absorpt_correction_T_max  1
_exptl_absorpt_correction_T_min  0.769670
_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details   'Blessing, 1995'
_exptl_crystal_colour            yellow
_exptl_crystal_density_diffrn    1.071
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             1408
_exptl_crystal_size_max          0.14
_exptl_crystal_size_mid          0.14
_exptl_crystal_size_min          0.07
_platon_squeeze_details
;
Squeeze was used to remove highly disordered hydrocarbon chains.  
The co-crystallized solvent was well-separated from the Nb complex, 
and its removal had negligible impact on the bonding within 
the remaining structure. 
;
_refine_diff_density_max         0.830
_refine_diff_density_min         -0.468
_refine_diff_density_rms         0.075
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.01(5)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.021
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     388
_refine_ls_number_reflns         6838
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.021
_refine_ls_R_factor_all          0.0771
_refine_ls_R_factor_gt           0.0570
_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^)+(0.0500P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1246
_refine_ls_wR_factor_ref         0.1333
_reflns_number_gt                5384
_reflns_number_total             6838
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            om1002528_si_001.cif
_cod_data_source_block           (mad)pyNb(NtBu)(NAr)
_cod_original_cell_volume        4099(13)
_cod_original_sg_symbol_H-M      'P 2(1) 2(1) 2(1)'
_cod_database_code               4066021