Fluorenyl-Tethered N-Heterocyclic Carbene Complexes of the Heavy Alkali Metals
Burnett, Stuart; Kennedy, Alan; Mansell, Stephen M.; Weetman, Catherine Ellen; Chemical Communications  (2026) –; doi:10.1039/D5CC06477E

data_7135309
_publ_section_title
;
 Fluorenyl-Tethered N-Heterocyclic Carbene Complexes of the Heavy Alkali
 Metals
;
_journal_name_full               'Chemical Communications'
_journal_paper_doi               10.1039/D5CC06477E
_journal_year                    2026
_chemical_formula_sum            'C46 H69 Cs2 Li N4 Si4'
_chemical_formula_weight         1063.17
_chemical_properties_physical
Air-sensitive,Moisture-sensitive,Oxygen-sensitive
_space_group_crystal_system      orthorhombic
_space_group_IT_number           29
_space_group_name_Hall           'P 2c -2ac'
_space_group_name_H-M_alt        'P c a 21'
_atom_sites_solution_hydrogens   geom
_audit_creation_method           SHELXL-2018/3
_audit_update_record
;
2025-11-10 deposited with the CCDC.	2025-12-04 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   25.3737(3)
_cell_length_b                   12.0154(1)
_cell_length_c                   17.5574(2)
_cell_measurement_reflns_used    12318
_cell_measurement_temperature    200(2)
_cell_measurement_theta_max      71.3100
_cell_measurement_theta_min      3.4880
_cell_volume                     5352.82(10)
_computing_cell_refinement       CrysalisPro
_computing_data_collection       CrysalisPro
_computing_data_reduction        CrysalisPro
_computing_publication_material  'SHELXL in WinGX'
_computing_structure_refinement  'SHELXL-2018/3 (Sheldrick, 2018)'
_computing_structure_solution    'SHELXT 2018/2 (Sheldrick, 2018)'
_diffrn_ambient_temperature      200(2)
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.998
_diffrn_measurement_device_type  'Rigaku Synergy-i'
_diffrn_measurement_method       'omega scans'
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54184
_diffrn_reflns_av_R_equivalents  0.0426
_diffrn_reflns_av_unetI/netI     0.0495
_diffrn_reflns_Laue_measured_fraction_full 0.999
_diffrn_reflns_Laue_measured_fraction_max 0.998
_diffrn_reflns_limit_h_max       30
_diffrn_reflns_limit_h_min       -30
_diffrn_reflns_limit_k_max       14
_diffrn_reflns_limit_k_min       -8
_diffrn_reflns_limit_l_max       21
_diffrn_reflns_limit_l_min       -21
_diffrn_reflns_number            29964
_diffrn_reflns_point_group_measured_fraction_full 0.939
_diffrn_reflns_point_group_measured_fraction_max 0.930
_diffrn_reflns_theta_full        67.684
_diffrn_reflns_theta_max         70.000
_diffrn_reflns_theta_min         4.071
_diffrn_source                   'microsource tube'
_exptl_absorpt_coefficient_mu    11.714
_exptl_absorpt_correction_T_max  0.742
_exptl_absorpt_correction_T_min  0.182
_exptl_absorpt_correction_type   gaussian
_exptl_absorpt_process_details
;
CrysAlisPro 1.171.41.115a (Rigaku Oxford Diffraction, 2021)
Numerical absorption correction based on gaussian integration over
a multifaceted crystal model
Empirical absorption correction using spherical harmonics,
implemented in SCALE3 ABSPACK scaling algorithm.
;
_exptl_crystal_colour            red
_exptl_crystal_density_diffrn    1.319
_exptl_crystal_description       fragment
_exptl_crystal_F_000             2168
_exptl_crystal_size_max          0.25
_exptl_crystal_size_mid          0.10
_exptl_crystal_size_min          0.10
_refine_diff_density_max         3.374
_refine_diff_density_min         -1.847
_refine_diff_density_rms         0.109
_refine_ls_abs_structure_details
;
 Refined as an inversion twin.
;
_refine_ls_abs_structure_Flack   0.123(16)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.027
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     528
_refine_ls_number_reflns         9458
_refine_ls_number_restraints     147
_refine_ls_restrained_S_all      1.024
_refine_ls_R_factor_all          0.0912
_refine_ls_R_factor_gt           0.0789
_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^)+(0.0758P)^2^+34.9050P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1982
_refine_ls_wR_factor_ref         0.2063
_reflns_Friedel_coverage         0.799
_reflns_Friedel_fraction_full    0.874
_reflns_Friedel_fraction_max     0.857
_reflns_number_gt                7783
_reflns_number_total             9458
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d5cc06477e2.cif
_cod_data_source_block           SB067_4
_cod_original_cell_volume        5352.81(10)
_cod_database_code               7135309
_shelx_shelxl_version_number     2018/3
_shelx_estimated_absorpt_t_min   0.158
_shelx_estimated_absorpt_t_max   0.387
_shelx_res_checksum              68502
_shelx_hkl_checksum              60635