[ICl4]-: A Large Anisotropic Planar Anion Group Produces Giant Birefringence
Liu, Yi-Chen; Zhang, Ming-Zhi; Hu, Chun-Li; Mao, Jiang-Gao; Chemical Communications  (2026) –; doi:10.1039/D6CC00713A

data_7135625
_publ_section_title
;
 [ICl<sub>4</sub>]<sup>-</sup>: A large anisotropic planar anion group
 produces giant birefringence.
;
_journal_issue                   28
_journal_name_full               'Chemical communications (Cambridge, England)'
_journal_page_first              7394
_journal_page_last               7398
_journal_paper_doi               10.1039/d6cc00713a
_journal_volume                  62
_journal_year                    2026
_chemical_formula_moiety         'Cl4 I, C5 H7 N2'
_chemical_formula_sum            'C5 H7 Cl4 I N2'
_chemical_formula_weight         363.83
_space_group_crystal_system      monoclinic
_space_group_IT_number           11
_space_group_name_Hall           '-P 2yb'
_space_group_name_H-M_alt        'P 1 21/m 1'
_atom_sites_solution_hydrogens   mixed
_atom_sites_solution_primary     iterative
_audit_creation_date             2026-01-14
_audit_creation_method
;
Olex2 1.5
(compiled 2025.07.13 svn.rb7424aed for OlexSys, GUI svn.r7314)
;
_audit_update_record
;
2026-01-14 deposited with the CCDC.	2026-03-13 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 93.656(11)
_cell_angle_gamma                90
_cell_formula_units_Z            2
_cell_length_a                   4.0937(5)
_cell_length_b                   11.9204(15)
_cell_length_c                   11.0250(16)
_cell_measurement_reflns_used    1950
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      28.4150
_cell_measurement_theta_min      3.6620
_cell_volume                     536.91(12)
_computing_molecular_graphics    'Olex2 1.5 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 1.5 (Dolomanov et al., 2009)'
_computing_structure_refinement  'SHELXL 2018/3 (Sheldrick, 2015)'
_computing_structure_solution    'olex2.solve 1.5 (Bourhis et al., 2015)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.997
_diffrn_measured_fraction_theta_max 0.873
_diffrn_measurement_device_type  'Bruker APEX-II CCD'
_diffrn_measurement_method       '\f and \w scans'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0460
_diffrn_reflns_av_unetI/netI     0.0536
_diffrn_reflns_Laue_measured_fraction_full 0.997
_diffrn_reflns_Laue_measured_fraction_max 0.873
_diffrn_reflns_limit_h_max       5
_diffrn_reflns_limit_h_min       -5
_diffrn_reflns_limit_k_max       15
_diffrn_reflns_limit_k_min       -15
_diffrn_reflns_limit_l_max       13
_diffrn_reflns_limit_l_min       -14
_diffrn_reflns_number            3762
_diffrn_reflns_point_group_measured_fraction_full 0.997
_diffrn_reflns_point_group_measured_fraction_max 0.873
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         29.071
_diffrn_reflns_theta_min         2.519
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    3.927
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            'clear yellowish yellow'
_exptl_crystal_colour_lustre     clear
_exptl_crystal_colour_modifier   yellowish
_exptl_crystal_colour_primary    yellow
_exptl_crystal_density_diffrn    2.250
_exptl_crystal_description       needle
_exptl_crystal_F_000             344
_exptl_crystal_size_max          0.01
_exptl_crystal_size_mid          0.001
_exptl_crystal_size_min          0.001
_refine_diff_density_max         1.137
_refine_diff_density_min         -0.944
_refine_diff_density_rms         0.189
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.075
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     61
_refine_ls_number_reflns         1317
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.075
_refine_ls_R_factor_all          0.0482
_refine_ls_R_factor_gt           0.0364
_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^)+(0.0393P)^2^] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0813
_refine_ls_wR_factor_ref         0.0886
_reflns_Friedel_coverage         0.000
_reflns_number_gt                1096
_reflns_number_total             1317
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d6cc00713a2.cif
_cod_data_source_block           1
_cod_depositor_comments          'Adding full bibliography for 7135625.cif.'
_cod_database_code               7135625
_shelx_shelxl_version_number     2018/3
_shelx_estimated_absorpt_t_max   0.996
_shelx_estimated_absorpt_t_min   0.962
_olex2_refinement_description
;
1. Fixed Uiso
 At 1.2 times of:
  All C(H) groups, All N(H) groups
2.a Riding coordinates:
 N1(H1), N2(H2)
2.b Aromatic/amide H refined with riding coordinates:
 C1(H1A), C2(H2A)
;
_shelx_res_checksum              91710
_shelx_hkl_checksum              5529
_olex2_submission_special_instructions 'No special instructions were received'