B-B bond activation and NHC ring-expansion reactions of diboron(4) compounds, and accurate molecular structures of B2(NMe2)4, B2eg2, B2neop2 and B2pin2.
Eck, Martin; Würtemberger-Pietsch, Sabrina; Eichhorn, Antonius; Berthel, Johannes H. J.; Bertermann, Rüdiger; Paul, Ursula S. D.; Schneider, Heidi; Friedrich, Alexandra; Kleeberg, Christian; Radius, Udo; Marder, Todd B.; Dalton transactions (Cambridge, England : 2003) 46 (2017) 3661–3680; doi:10.1039/c7dt00334j

data_7042150
_publ_section_title
;
 B-B bond activation and NHC ring-expansion reactions of diboron(4)
 compounds, and accurate molecular structures of B2(NMe2)4, B2eg2, B2neop2
 and B2pin2.
;
_journal_issue                   11
_journal_name_full
'Dalton transactions (Cambridge, England : 2003)'
_journal_page_first              3661
_journal_page_last               3680
_journal_paper_doi               10.1039/c7dt00334j
_journal_volume                  46
_journal_year                    2017
_chemical_formula_moiety         'C8 H24 B2 N4'
_chemical_formula_sum            'C8 H24 B2 N4'
_chemical_formula_weight         197.93
_space_group_crystal_system      monoclinic
_space_group_IT_number           14
_space_group_name_Hall           '-P 2ybc'
_space_group_name_H-M_alt        'P 1 21/c 1'
_symmetry_space_group_name_Hall  '-P 2ybc'
_symmetry_space_group_name_H-M   'P 1 21/c 1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     iterative
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-2014/7
_audit_update_record
;
2017-01-27 deposited with the CCDC.
2017-02-21 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 99.851(5)
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   9.4204(5)
_cell_length_b                   8.8439(6)
_cell_length_c                   16.0580(8)
_cell_measurement_reflns_used    10485
_cell_measurement_temperature    185(2)
_cell_measurement_theta_max      27.06
_cell_measurement_theta_min      2.56
_cell_volume                     1318.12(13)
_computing_cell_refinement
;
 CrysAlisPro, Agilent Technologies,
 Version 1.171.36.24a (release 19-12-2012 CrysAlis171 .NET)
 (compiled Dec 19 2012,11:08:27)
;
_computing_data_collection
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 CrysAlisPro, Agilent Technologies,
 Version 1.171.36.24a (release 19-12-2012 CrysAlis171 .NET)
 (compiled Dec 19 2012,11:08:27)
;
_computing_data_reduction
;
 CrysAlisPro, Agilent Technologies,
 Version 1.171.36.24a (release 19-12-2012 CrysAlis171 .NET)
 (compiled Dec 19 2012,11:08:27)
;
_computing_molecular_graphics
;
 K. Brandenburg, 1999, Diamond 3.2i, Crystal Impact GbR, Bonn, Germany.
;
_computing_publication_material
;
 WinGX v2014.1 (L. J. Farrugia, J. Appl. Cryst., 2012, 45, 849-854.)
;
_computing_structure_refinement
;
 SHELXL-2014/7 (G. M. Sheldrick, Acta Cryst. (2008), A64, 112-122)'
;
_computing_structure_solution
;
 SHELXT (Ver. 2014/4) (G. M. Sheldrick, Acta Cryst., 2015, A71, 3--8)
;
_diffrn_ambient_temperature      185(2)
_diffrn_detector_area_resol_mean 16.1419
_diffrn_measured_fraction_theta_full 0.922
_diffrn_measured_fraction_theta_max 0.922
_diffrn_measurement_device_type  'Oxford Diffraction, Xcalibur, EOS'
_diffrn_measurement_method       \p-scan
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'Enhance (Mo) X-ray Source'
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0440
_diffrn_reflns_av_unetI/netI     0.0156
_diffrn_reflns_Laue_measured_fraction_full 0.922
_diffrn_reflns_Laue_measured_fraction_max 0.922
_diffrn_reflns_limit_h_max       11
_diffrn_reflns_limit_h_min       -11
_diffrn_reflns_limit_k_max       9
_diffrn_reflns_limit_k_min       -7
_diffrn_reflns_limit_l_max       18
_diffrn_reflns_limit_l_min       -19
_diffrn_reflns_number            37371
_diffrn_reflns_point_group_measured_fraction_full 0.922
_diffrn_reflns_point_group_measured_fraction_max 0.922
_diffrn_reflns_theta_full        24.998
_diffrn_reflns_theta_max         24.998
_diffrn_reflns_theta_min         2.575
_exptl_absorpt_coefficient_mu    0.060
_exptl_absorpt_correction_T_max  1.000
_exptl_absorpt_correction_T_min  0.831
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
 CrysAlisPro, Agilent Technologies,
 Version 1.171.36.24a (release 19-12-2012 CrysAlis171 .NET)
 (compiled Dec 19 2012,11:08:27)
 Empirical absorption correction using spherical harmonics,
 implemented in SCALE3 ABSPACK scaling algorithm.
;
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    0.997
_exptl_crystal_description       irregular
_exptl_crystal_F_000             440
_exptl_crystal_recrystallization_method
'B2(NMe2)4 was crystallised in situ. Pure B2(NMe2)4 was enclosed in a glass capillary of 1.0 mm outer diameter that narrows at one end into a cone. The capillary was filled with ca. 0.1 /mL of B2(NMe2)4. The capillary was  flame sealed and glued into a brass pin that was mounted on the goniometer head. A part of the conical section of this capillary was centered in the  X-ray beam (0.5 mm dia.), so that a conical section of the capillary filled  with B2(NMe2)4 was exposed to the X-ray beam (bottom diameter: 0.42 mm, top diameter: 0.19 mm). The axis of the capillary was aligned parallel to nitrogen gas stream of the cryostat. The temperature was gradually (within 3 h) lowered from rt to 200 K whereupon the B2(NMe2)4 crystallised upon shock-cooling with a drop of liquid nitrogen; the poly crystalline mass was found to melt at approx. 205 K. Sequences of cooling to 200 - 195 K, annealing, shock-cooling, reheating to 210K were repeated until the diffraction pattern indicated that a reasonably single crystalline sample had formed. Finally the temperature was lowered to 185 K.'
_exptl_crystal_size_max          0.50
_exptl_crystal_size_mid          0.42
_exptl_crystal_size_min          0.19
_refine_diff_density_max         0.214
_refine_diff_density_min         -0.139
_refine_diff_density_rms         0.034
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.161
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     135
_refine_ls_number_reflns         2143
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.161
_refine_ls_R_factor_all          0.0646
_refine_ls_R_factor_gt           0.0589
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0634P)^2^+0.6341P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1553
_refine_ls_wR_factor_ref         0.1587
_reflns_number_gt                1954
_reflns_number_total             2143
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            c7dt00334j2.cif
_cod_data_source_block           ck42ck
_cod_depositor_comments
'Adding full bibliography for 7042146--7042160.cif.'
_cod_database_code               7042150
_shelx_shelxl_version_number     2014/7
_shelx_res_checksum              61604