Heteroleptic tethered NHC rare earth initiators for the ring opening polymerisation of <i>rac</i>-lactide.
Walker, Joseph W.; Chowdhury, Tajrian; Rosair, Georgina M.; Farnaby, Joy H.; Mansell, Stephen M.; McIntosh, Ruaraidh D.; Dalton transactions (Cambridge, England : 2003) 54 (2025) 14937–14946; doi:10.1039/d5dt01352f

data_1575800
_publ_section_title
;
 Heteroleptic tethered NHC rare earth initiators for the ring opening
 polymerisation of <i>rac</i>-lactide.
;
_journal_issue                   39
_journal_name_full
'Dalton transactions (Cambridge, England : 2003)'
_journal_page_first              14937
_journal_page_last               14946
_journal_paper_doi               10.1039/d5dt01352f
_journal_volume                  54
_journal_year                    2025
_chemical_formula_moiety         'C31 H53 La N4 Si4'
_chemical_formula_sum            'C31 H53 La N4 Si4'
_chemical_formula_weight         733.04
_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
_atom_sites_solution_primary     dual
_audit_creation_date             2024-09-01
_audit_creation_method
;
Olex2 1.2
(compiled 2018.05.29 svn.r3508 for OlexSys, GUI svn.r5506)
;
_audit_update_record
;
2025-08-11 deposited with the CCDC.	2025-09-16 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   12.9434(2)
_cell_length_b                   16.4994(2)
_cell_length_c                   16.8840(2)
_cell_measurement_reflns_used    9915
_cell_measurement_temperature    100.0
_cell_measurement_theta_max      74.316
_cell_measurement_theta_min      6.812
_cell_volume                     3605.72(8)
_computing_cell_refinement       'SAINT V8.40B (?, 2016)'
_computing_data_collection       'Bruker Apex4 v2022.10-0 (Bruker, 2022)'
_computing_data_reduction        'SAINT V8.40B (?, 2016)'
_computing_molecular_graphics    'Olex2 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 (Dolomanov et al., 2009)'
_computing_structure_refinement  'ShelXL (Sheldrick, 2015)'
_computing_structure_solution    'XT (Sheldrick, 2015)'
_diffrn_ambient_temperature      100.0
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 0.956
_diffrn_measurement_device_type  'Bruker D8 Venture'
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54178
_diffrn_reflns_av_R_equivalents  0.0737
_diffrn_reflns_av_unetI/netI     0.0354
_diffrn_reflns_Laue_measured_fraction_full 1.000
_diffrn_reflns_Laue_measured_fraction_max 0.956
_diffrn_reflns_limit_h_max       15
_diffrn_reflns_limit_h_min       -15
_diffrn_reflns_limit_k_max       20
_diffrn_reflns_limit_k_min       -20
_diffrn_reflns_limit_l_max       20
_diffrn_reflns_limit_l_min       -20
_diffrn_reflns_number            80345
_diffrn_reflns_point_group_measured_fraction_full 1.000
_diffrn_reflns_point_group_measured_fraction_max 0.955
_diffrn_reflns_theta_full        67.679
_diffrn_reflns_theta_max         71.986
_diffrn_reflns_theta_min         2.617
_exptl_absorpt_coefficient_mu    10.616
_exptl_absorpt_correction_T_max  0.7538
_exptl_absorpt_correction_T_min  0.5212
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
SADABS-2016/2 (Bruker,2016/2) was used for absorption correction.
wR2(int) was 0.1072 before and 0.0558 after correction.
The Ratio of minimum to maximum transmission is 0.6914.
The \l/2 correction factor is Not present.
;
_exptl_crystal_colour            orange
_exptl_crystal_colour_primary    orange
_exptl_crystal_density_diffrn    1.350
_exptl_crystal_description       block
_exptl_crystal_F_000             1520
_exptl_crystal_size_max          0.181
_exptl_crystal_size_mid          0.167
_exptl_crystal_size_min          0.149
_refine_diff_density_max         9.955
_refine_diff_density_min         -2.790
_refine_diff_density_rms         0.599
_refine_ls_abs_structure_details
;
 Twinning involves inversion, so Flack parameter cannot be determined
;
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.058
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     377
_refine_ls_number_reflns         7433
_refine_ls_number_restraints     13
_refine_ls_restrained_S_all      1.058
_refine_ls_R_factor_all          0.0765
_refine_ls_R_factor_gt           0.0704
_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^)+(0.1397P)^2^+9.8308P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1775
_refine_ls_wR_factor_ref         0.1833
_reflns_Friedel_coverage         0.927
_reflns_Friedel_fraction_full    1.000
_reflns_Friedel_fraction_max     0.954
_reflns_number_gt                6715
_reflns_number_total             7433
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d5dt01352f2.cif
_cod_data_source_block           5_LaLN2
_cod_depositor_comments
'Adding full bibliography for 1575797--1575801.cif.'
_cod_database_code               1575800
_shelx_shelxl_version_number     2018/3
_shelx_estimated_absorpt_t_max   0.301
_shelx_estimated_absorpt_t_min   0.250
_olex2_refinement_description
;
1. Twinned data refinement
 Scales: 0.628(10)
 0.0014(19) 0.370(10) 0.0008(19)
2. Fixed Uiso
 At 1.2 times of:
  All C(H) groups, All C(H,H) groups
 At 1.5 times of:
  All C(H,H,H) groups
3. Uiso/Uaniso restraints and constraints
Uanis(C2) \\sim Ueq, Uanis(C16) \\sim Ueq: with sigma of 0.005 and sigma for
terminal atoms of 0.01
4.a Secondary CH2 refined with riding coordinates:
 C14(H14A,H14B), C15(H15A,H15B)
4.b Aromatic/amide H refined with riding coordinates:
 C3(H3), C4(H4), C5(H5), C6(H6), C9(H9), C10(H10), C11(H11), C12(H12),
 C17(H17), C18(H18)
4.c Idealised Me refined as rotating group:
 C19(H19A,H19B,H19C), C20(H20A,H20B,H20C), C21(H21A,H21B,H21C), C22(H22A,H22B,
 H22C), C23(H23A,H23B,H23C), C24(H24A,H24B,H24C), C25(H25A,H25B,H25C), C26(H26A,
 H26B,H26C), C27(H27C,H27A,H27B), C28(H28A,H28B,H28C), C29(H29A,H29B,H29C),
 C30(H30A,H30B,H30C), C31(H31A,H31B,H31C)
;
_shelx_res_checksum              3261
_olex2_submission_special_instructions 'No special instructions were received'