Exploiting π-type halogen bonds as a means to achieve mixed co-crystals: crystallographic and computational evidence of a Cl⋯π halogen bond in the organic solid state
Feld, Emmett H.; Bosch, Eric; Unruh, Daniel K.; Krueger, Herman R.; Groeneman, Ryan H.; CrystEngComm 28 (2026) 1770–1774; doi:10.1039/D6CE00047A

data_7251664
_publ_section_title
;
 Exploiting \p-type halogen bonds as a means to achieve mixed co-crystals:
 crystallographic and computational evidence of a Cl&#x22EF;\p halogen
 bond in the organic solid state
;
_journal_issue                   11
_journal_name_full               CrystEngComm
_journal_page_first              1770
_journal_page_last               1774
_journal_paper_doi               10.1039/D6CE00047A
_journal_volume                  28
_journal_year                    2026
_chemical_formula_moiety         'C6 Cl4.30 I1.70, 2(C7 H6 O2)'
_chemical_formula_sum            'C20 H12 Cl4.3 I1.7 O4'
_chemical_formula_weight         684.46
_space_group_crystal_system      triclinic
_space_group_IT_number           2
_space_group_name_Hall           '-P 1'
_space_group_name_H-M_alt        'P -1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     dual
_audit_creation_date             2025-09-05
_audit_creation_method
;
Olex2 1.5
(compiled 2025.07.13 svn.rb7424aed for OlexSys, GUI svn.r7314)
;
_audit_update_record
;
2026-01-13 deposited with the CCDC.	2026-02-23 downloaded from the CCDC.
;
_cell_angle_alpha                100.7290(10)
_cell_angle_beta                 94.1290(10)
_cell_angle_gamma                98.9660(10)
_cell_formula_units_Z            1
_cell_length_a                   5.3509(2)
_cell_length_b                   6.4894(3)
_cell_length_c                   16.2659(6)
_cell_measurement_reflns_used    9509
_cell_measurement_temperature    100.00
_cell_measurement_theta_max      28.345
_cell_measurement_theta_min      2.563
_cell_volume                     545.19(4)
_computing_cell_refinement       'SAINT V8.41 (Bruker AXS Inc, 2024)'
_computing_data_reduction        'SAINT V8.41 (Bruker AXS Inc, 2024)'
_computing_molecular_graphics    'Olex2 1.5 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 1.5 (Dolomanov et al., 2009)'
_computing_structure_refinement  'XL  (Sheldrick, 2008)'
_computing_structure_solution    'SHELXT 2018/2 (Sheldrick, 2018)'
_diffrn_ambient_temperature      100.00
_diffrn_measured_fraction_theta_full 0.984
_diffrn_measured_fraction_theta_max 0.988
_diffrn_measurement_device_type  'Bruker D8 Venture DUO with Photon 3'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0285
_diffrn_reflns_av_unetI/netI     0.0130
_diffrn_reflns_Laue_measured_fraction_full 0.984
_diffrn_reflns_Laue_measured_fraction_max 0.988
_diffrn_reflns_limit_h_max       7
_diffrn_reflns_limit_h_min       -7
_diffrn_reflns_limit_k_max       8
_diffrn_reflns_limit_k_min       -8
_diffrn_reflns_limit_l_max       21
_diffrn_reflns_limit_l_min       -21
_diffrn_reflns_number            33268
_diffrn_reflns_point_group_measured_fraction_full 0.984
_diffrn_reflns_point_group_measured_fraction_max 0.988
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         28.396
_diffrn_reflns_theta_min         2.563
_diffrn_source_current           1.4
_diffrn_source_power             0.07
_diffrn_source_voltage           50.0
_exptl_absorpt_coefficient_mu    3.013
_exptl_absorpt_correction_T_max  0.2627
_exptl_absorpt_correction_T_min  0.2153
_exptl_absorpt_correction_type   numerical
_exptl_absorpt_process_details
;
SADABS-2016/2 (Bruker,2016/2) was used for absorption correction.
wR2(int) was 0.0606 before and 0.0391 after correction.
The Ratio of minimum to maximum transmission is 0.8196.
The \l/2 correction factor is Not present.
;
_exptl_crystal_colour            'clear colourless'
_exptl_crystal_colour_lustre     clear
_exptl_crystal_colour_primary    colourless
_exptl_crystal_density_diffrn    2.085
_exptl_crystal_description       irregular
_exptl_crystal_F_000             327
_exptl_crystal_size_max          0.192
_exptl_crystal_size_mid          0.176
_exptl_crystal_size_min          0.131
_refine_diff_density_max         0.390
_refine_diff_density_min         -0.285
_refine_diff_density_rms         0.053
_refine_ls_extinction_coef       0.0056(5)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     'SHELXL-2019/2 (Sheldrick 2019)'
_refine_ls_goodness_of_fit_ref   1.144
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     142
_refine_ls_number_reflns         2705
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.144
_refine_ls_R_factor_all          0.0124
_refine_ls_R_factor_gt           0.0121
_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^)+(0.0059P)^2^+0.2815P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0289
_refine_ls_wR_factor_ref         0.0290
_reflns_Friedel_coverage         0.000
_reflns_number_gt                2667
_reflns_number_total             2705
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d6ce00047a2.cif
_cod_data_source_block           C6I2Cl4_C6ICl5_BAc
_cod_depositor_comments
'Adding full bibliography for 7251664--7251666.cif.'
_cod_original_formula_sum        'C20 H12 Cl4.30 I1.70 O4'
_cod_database_code               7251664
_shelx_shelxl_version_number     2019/3
_shelx_estimated_absorpt_t_max   0.694
_shelx_estimated_absorpt_t_min   0.595
_olex2_refinement_description
;
1. Fixed Uiso
 At 1.2 times of:
  All C(H) groups
 At 1.5 times of:
  All O(H) groups
2. Uiso/Uaniso restraints and constraints
Uanis(Cl3) = Uanis(I1)
3. Others
 Sof(Cl3)=1-FVAR(1)
 Sof(I1)=FVAR(1)
4.a Aromatic/amide H refined with riding coordinates:
 C7(H7), C8(H8), C9(H9), C5(H5), C6(H6)
4.b Idealised tetrahedral OH refined as rotating group:
 O1(H1)
;
_shelx_res_checksum              59674
_olex2_exptl_crystal_mounting_method 'MiTeGen 100 micron MicroLoop'
_olex2_submission_special_instructions 'No special instructions were received'