Zwitterionic borane adducts of N-heterocyclic carbenes from mesomeric betaines of uracil.
Zhang, Jiaxi; Pidlypnyi, Nazar; Nieger, Martin; Namyslo, Jan C.; Schmidt, Andreas; Organic & biomolecular chemistry 12 (2014) 2737–2744; doi:10.1039/c3ob42462f

data_7153725
_publ_section_title
;
 Zwitterionic borane adducts of N-heterocyclic carbenes from mesomeric
 betaines of uracil.
;
_journal_issue                   17
_journal_name_full               'Organic &amp; biomolecular chemistry'
_journal_page_first              2737
_journal_page_last               2744
_journal_paper_doi               10.1039/c3ob42462f
_journal_volume                  12
_journal_year                    2014
_chemical_formula_moiety         'C18 H21 B N4 O2'
_chemical_formula_sum            'C18 H21 B N4 O2'
_chemical_formula_weight         336.20
_chemical_name_systematic
;
 1-benzyl-10,10-diethyl-6,8-dioxo-6,7,8,10-tetrahydro-1H-imidazo
[2',1:3,4][1,4,2]diazaborolo[1,5-c]pyrimidin-4-ium-10-uide
;
_space_group_crystal_system      orthorhombic
_space_group_IT_number           33
_space_group_name_Hall           'P 2c -2n'
_space_group_name_H-M_alt        'P n a 21'
_symmetry_space_group_name_Hall  'P 2c -2n'
_symmetry_space_group_name_H-M   'P n a 21'
_atom_sites_solution_hydrogens   difmap
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-2013
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            8
_cell_length_a                   35.612(3)
_cell_length_b                   8.829(1)
_cell_length_c                   11.287(1)
_cell_measurement_reflns_used    182
_cell_measurement_temperature    123(2)
_cell_measurement_theta_max      25.0
_cell_measurement_theta_min      2.5
_cell_volume                     3548.8(6)
_computing_cell_refinement       EVALCCD
_computing_data_collection       Collect
_computing_data_reduction        EVALCCD
_computing_molecular_graphics    SHELXTL-Plus
_computing_publication_material  publCif
_computing_structure_refinement  'SHELXL-2013 (Sheldrick, 2013)'
_computing_structure_solution    SHELXS-97
_diffrn_ambient_temperature      123(2)
_diffrn_measured_fraction_theta_full 0.996
_diffrn_measured_fraction_theta_max 0.996
_diffrn_measurement_device_type  'Bruker-Nonius KappaCCD'
_diffrn_measurement_method       'rotation in \f and \w, 0.5\%'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0333
_diffrn_reflns_av_unetI/netI     0.0384
_diffrn_reflns_Laue_measured_fraction_full 0.996
_diffrn_reflns_Laue_measured_fraction_max 0.996
_diffrn_reflns_limit_h_max       45
_diffrn_reflns_limit_h_min       -46
_diffrn_reflns_limit_k_max       10
_diffrn_reflns_limit_k_min       -11
_diffrn_reflns_limit_l_max       14
_diffrn_reflns_limit_l_min       -14
_diffrn_reflns_number            22454
_diffrn_reflns_point_group_measured_fraction_full 0.946
_diffrn_reflns_point_group_measured_fraction_max 0.923
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         27.483
_diffrn_reflns_theta_min         2.575
_diffrn_source                   'fine-focus sealed tube'
_exptl_absorpt_coefficient_mu    0.083
_exptl_absorpt_correction_T_max  0.9866
_exptl_absorpt_correction_T_min  0.9352
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'SADABS (Sheldrick, 2008)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.258
_exptl_crystal_description       blocks
_exptl_crystal_F_000             1424
_exptl_crystal_size_max          0.400
_exptl_crystal_size_mid          0.300
_exptl_crystal_size_min          0.200
_refine_diff_density_max         0.306
_refine_diff_density_min         -0.219
_refine_diff_density_rms         0.044
_refine_ls_abs_structure_details
;
 Flack x determined using 2474 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons and Flack (2004), Acta Cryst. A60, s61).
;
_refine_ls_abs_structure_Flack   -0.7(5)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.120
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     457
_refine_ls_number_reflns         7540
_refine_ls_number_restraints     3
_refine_ls_restrained_S_all      1.120
_refine_ls_R_factor_all          0.0624
_refine_ls_R_factor_gt           0.0505
_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^)+(0.0528P)^2^+0.8778P]
 where P=(Fo^2^+2Fc^2^)/3
;
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1120
_refine_ls_wR_factor_ref         0.1174
_reflns_Friedel_coverage         0.765
_reflns_Friedel_fraction_full    0.891
_reflns_Friedel_fraction_max     0.843
_reflns_number_gt                6456
_reflns_number_total             7540
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            c3ob42462f2.cif
_cod_data_source_block           schm59_o_compound_26d
_cod_database_code               7153725
_shelx_estimated_absorpt_t_min   0.967
_shelx_estimated_absorpt_t_max   0.984
_shelxl_version_number           2013-2
_shelx_res_checksum              17783