The reactivity of 1,1-dialkoxyalkanes with niobium and tantalum pentahalides. Formation of coordination compounds, C‒H and C‒C bond activation and the X-ray structure of the stable carboxonium species [Me2CCHC(OMe)Me][NbCl5(OMe)]
Marchetti, Fabio; Pampaloni, Guido; Zacchini, Stefano; Dalton Transactions  (2009) 8096–8106; doi:10.1039/b907774j

data_7002337
_publ_section_title
;
 The reactivity of 1,1-dialkoxyalkanes with niobium and tantalum
 pentahalides. Formation of coordination compounds, C--H and C--C bond
 activation and the X-ray structure of the stable carboxonium species
 [Me2C&#xE001;CHC(&#xE001;OMe)Me][NbCl5(OMe)]
;
_journal_issue                   38
_journal_name_full               'Dalton Transactions'
_journal_page_first              8096
_journal_page_last               8106
_journal_paper_doi               10.1039/b907774j
_journal_year                    2009
_chemical_formula_sum            'C4 H12 Br6 O4 Ta2'
_chemical_formula_weight         965.50
_chemical_name_systematic
;
?
;
_space_group_IT_number           2
_symmetry_cell_setting           triclinic
_symmetry_space_group_name_Hall  '-P 1'
_symmetry_space_group_name_H-M   'P -1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                75.974(7)
_cell_angle_beta                 80.170(8)
_cell_angle_gamma                76.556(8)
_cell_formula_units_Z            1
_cell_length_a                   6.510(4)
_cell_length_b                   7.174(4)
_cell_length_c                   9.206(5)
_cell_measurement_reflns_used    2205
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      27.778
_cell_measurement_theta_min      2.297
_cell_volume                     402.7(4)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      100(2)
_diffrn_measured_fraction_theta_full 0.989
_diffrn_measured_fraction_theta_max 0.989
_diffrn_measurement_device_type  'CCD area detector'
_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  0.0493
_diffrn_reflns_av_sigmaI/netI    0.0594
_diffrn_reflns_limit_h_max       7
_diffrn_reflns_limit_h_min       -7
_diffrn_reflns_limit_k_max       8
_diffrn_reflns_limit_k_min       -8
_diffrn_reflns_limit_l_max       10
_diffrn_reflns_limit_l_min       -10
_diffrn_reflns_number            3442
_diffrn_reflns_theta_full        25.02
_diffrn_reflns_theta_max         25.02
_diffrn_reflns_theta_min         2.30
_exptl_absorpt_coefficient_mu    28.453
_exptl_absorpt_correction_T_max  0.1631
_exptl_absorpt_correction_T_min  0.1089
_exptl_absorpt_correction_type   empirical
_exptl_crystal_colour            pale-yellow
_exptl_crystal_density_diffrn    3.981
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       plate
_exptl_crystal_F_000             424
_exptl_crystal_size_max          0.11
_exptl_crystal_size_mid          0.10
_exptl_crystal_size_min          0.10
_refine_diff_density_max         6.828
_refine_diff_density_min         -3.193
_refine_diff_density_rms         0.657
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.106
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     75
_refine_ls_number_reflns         1409
_refine_ls_number_restraints     19
_refine_ls_restrained_S_all      1.111
_refine_ls_R_factor_all          0.0940
_refine_ls_R_factor_gt           0.0746
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.1047P)^2^+38.0200P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1949
_refine_ls_wR_factor_ref         0.2086
_reflns_number_gt                1114
_reflns_number_total             1409
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            b907774j.txt
_cod_data_source_block           pp-1
_cod_original_sg_symbol_H-M      P-1
_cod_database_code               7002337