Synthesis and structural characterisation of [TpMe2Nb(CH3)2(CH3CCCH3)] and [TpMe2NbCl(CH3)(CH3CCCH3)]: is there an intrinsic α-agostic interaction in alkyl complexes of the [TpMe2Nb(alkyne)] moiety?
Teuma, Emmanuelle; Etienne, Michel; Donnadieu, Bruno; McGrady, G. Sean; New Journal of Chemistry 30 (2006) 409–; doi:10.1039/b514820k

data_7051543
_publ_section_title
;
 Synthesis and structural characterisation of
 [TpMe2Nb(CH3)2(CH3C&#xE002;CCH3)] and
 [TpMe2NbCl(CH3)(CH3C&#xE002;CCH3)]: is there an intrinsic \a-agostic
 interaction in alkyl complexes of the [TpMe2Nb(alkyne)] moiety?
;
_journal_issue                   3
_journal_name_full               'New Journal of Chemistry'
_journal_page_first              409
_journal_paper_doi               10.1039/b514820k
_journal_volume                  30
_journal_year                    2006
_chemical_formula_sum            'C21 H34 B N6 Nb'
_chemical_formula_weight         474.26
_chemical_name_systematic
;
?
;
_space_group_IT_number           29
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  'P 2c -2ac'
_symmetry_space_group_name_H-M   'P c a 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                   10.1222(13)
_cell_length_b                   13.6129(13)
_cell_length_c                   16.5563(15)
_cell_measurement_reflns_used    8000
_cell_measurement_temperature    160(2)
_cell_measurement_theta_max      24.7
_cell_measurement_theta_min      2.0
_cell_volume                     2281.3(4)
_computing_cell_refinement       'Stoe IPDS software (Stoe, 1996)'
_computing_data_collection       'Stoe IPDS software (Stoe, 1996)'
_computing_data_reduction        'XRED (Stoe, 1.08, 1996)'
_computing_molecular_graphics    'ORTEP3 for Windows (Farrugia, 1997)'
_computing_publication_material  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SIR92 (Giacovazzo et al, 1992)'
_diffrn_ambient_temperature      160(2)
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.998
_diffrn_measurement_device       'Stoe IPDS'
_diffrn_measurement_method       \f
_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  0.0547
_diffrn_reflns_av_sigmaI/netI    0.0391
_diffrn_reflns_limit_h_max       11
_diffrn_reflns_limit_h_min       -11
_diffrn_reflns_limit_k_max       16
_diffrn_reflns_limit_k_min       -16
_diffrn_reflns_limit_l_max       18
_diffrn_reflns_limit_l_min       -19
_diffrn_reflns_number            15009
_diffrn_reflns_theta_full        24.70
_diffrn_reflns_theta_max         24.70
_diffrn_reflns_theta_min         2.51
_diffrn_standards_decay_%        0.1
_diffrn_standards_number         200
_exptl_absorpt_coefficient_mu    0.547
_exptl_absorpt_correction_T_max  0.8986
_exptl_absorpt_correction_T_min  0.8110
_exptl_absorpt_correction_type   refdelf
_exptl_crystal_colour            orange
_exptl_crystal_density_diffrn    1.381
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       'prism frag'
_exptl_crystal_F_000             992
_exptl_crystal_size_max          0.40
_exptl_crystal_size_mid          0.30
_exptl_crystal_size_min          0.20
_refine_diff_density_max         0.674
_refine_diff_density_min         -0.540
_refine_diff_density_rms         0.067
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   -0.03(5)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.002
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     276
_refine_ls_number_reflns         3828
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.002
_refine_ls_R_factor_all          0.0404
_refine_ls_R_factor_gt           0.0318
_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          0.0745
_refine_ls_wR_factor_ref         0.0776
_reflns_number_gt                3293
_reflns_number_total             3828
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            b514820k.txt
_cod_data_source_block           2
_cod_depositor_comments
;
The following automatic conversions were performed:
'_symmetry_cell_setting' value 'Orthorhombic' changed to 'orthorhombic'
according to '/home/saulius/struct/CIF-dictionaries/cif_core.dic'
dictionary named 'cif_core.dic' version 2.4.1 from 2010-06-29.

Automatic conversion script
Id: cif_fix_enum 1527 2010-12-29 10:47:43Z saulius 
;
_cod_original_sg_symbol_H-M      'P c a 2(1)'
_cod_database_code               7051543