Twisting the arm: structural constraints in bicyclic expanded-ring N-heterocyclic carbenes.
Sampford, Katharine R.; Carden, Jamie L.; Kidner, Edward B.; Berry, Abigail; Cavell, Kingsley J.; Murphy, Damien M.; Kariuki, Benson M.; Newman, Paul D.; Dalton transactions (Cambridge, England : 2003) 48 (2019) 1850–1858; doi:10.1039/c8dt04462g

data_7048655
_publ_section_title
;
 Twisting the arm: structural constraints in bicyclic expanded-ring
 N-heterocyclic carbenes.
;
_journal_issue                   5
_journal_name_full
'Dalton transactions (Cambridge, England : 2003)'
_journal_page_first              1850
_journal_page_last               1858
_journal_paper_doi               10.1039/c8dt04462g
_journal_volume                  48
_journal_year                    2019
_chemical_formula_moiety         'C18 H20 Au Cl N2'
_chemical_formula_sum            'C18 H20 Au Cl N2'
_chemical_formula_weight         496.78
_space_group_crystal_system      orthorhombic
_space_group_IT_number           19
_space_group_name_Hall           'P 2ac 2ab'
_space_group_name_H-M_alt        'P 21 21 21'
_symmetry_space_group_name_Hall  'P 2ac 2ab'
_symmetry_space_group_name_H-M   'P 21 21 21'
_atom_sites_solution_hydrogens   geom
_audit_creation_method           SHELXL-2018/1
_audit_update_record
;
2018-12-10 deposited with the CCDC.
2018-12-11 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   7.4368(3)
_cell_length_b                   13.2521(4)
_cell_length_c                   17.6939(6)
_cell_measurement_reflns_used    2281
_cell_measurement_temperature    150(2)
_cell_measurement_theta_max      27.485
_cell_measurement_theta_min      0.998
_cell_volume                     1743.79(11)
_computing_cell_refinement       'HKL Scalepack (Otwinowski & Minor 1997)'
_computing_data_collection       'Collect (Bruker AXS BV, 1997-2004)'
_computing_data_reduction
'HKL Denzo and Scalepack (Otwinowski & Minor 1997)'
_computing_molecular_graphics    ORTEP-3
_computing_publication_material  WinGX
_computing_structure_refinement  SHELXL
_computing_structure_solution    SHELXS
_diffrn_ambient_temperature      150(2)
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.998
_diffrn_measurement_device_type  KappaCCD
_diffrn_measurement_method       'CCD rotation images, thick slices'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0001
_diffrn_reflns_av_unetI/netI     0.0448
_diffrn_reflns_Laue_measured_fraction_full 0.999
_diffrn_reflns_Laue_measured_fraction_max 0.998
_diffrn_reflns_limit_h_max       7
_diffrn_reflns_limit_h_min       -7
_diffrn_reflns_limit_k_max       12
_diffrn_reflns_limit_k_min       -12
_diffrn_reflns_limit_l_max       17
_diffrn_reflns_limit_l_min       -17
_diffrn_reflns_number            3997
_diffrn_reflns_point_group_measured_fraction_full 0.999
_diffrn_reflns_point_group_measured_fraction_max 0.998
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         27.502
_diffrn_reflns_theta_min         1.920
_exptl_absorpt_coefficient_mu    8.587
_exptl_absorpt_correction_T_max  0.5120
_exptl_absorpt_correction_T_min  0.2227
_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details   sadabs
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.892
_exptl_crystal_description       needle
_exptl_crystal_F_000             952
_exptl_crystal_size_max          0.250
_exptl_crystal_size_mid          0.120
_exptl_crystal_size_min          0.090
_refine_diff_density_max         2.723
_refine_diff_density_min         -1.168
_refine_diff_density_rms         0.140
_refine_ls_abs_structure_details
;
 Refined as an inversion twin.
;
_refine_ls_abs_structure_Flack   0.49(2)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.060
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     255
_refine_ls_number_reflns         3997
_refine_ls_number_restraints     312
_refine_ls_restrained_S_all      1.026
_refine_ls_R_factor_all          0.0436
_refine_ls_R_factor_gt           0.0382
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0272P)^2^+10.8127P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0793
_refine_ls_wR_factor_ref         0.0813
_reflns_Friedel_coverage         0.745
_reflns_Friedel_fraction_full    0.999
_reflns_Friedel_fraction_max     0.999
_reflns_number_gt                3743
_reflns_number_total             3997
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            c8dt04462g2.cif
_cod_data_source_block           kjc1224
_cod_depositor_comments
'Adding full bibliography for 7048655--7048669.cif.'
_cod_database_code               7048655
_shelx_shelxl_version_number     2018/1
_shelx_estimated_absorpt_t_min   0.223
_shelx_estimated_absorpt_t_max   0.512
_shelx_res_checksum              85640