Tuning optical properties and local lone-pair off-centering in "hollow" FA<sub>1-<i>x</i></sub> {<i>en</i>} <sub><i>x</i></sub> Pb <sub><i>η</i>-<i>y</i></sub> Sn <sub><i>y</i></sub> Br<sub>3</sub> perovskites.
Balvanz, Adam; Pournara, Anastasia; Reynolds, Robert P.; Meza, Patricia E.; Malliakas, Christos D.; Fletcher, Jared D.; Seshadri, Ram; Dravid, Vinayak P.; Kanatzidis, Mercouri G.; Chemical science 17 (2026) 526–543; doi:10.1039/d5sc01841b

data_1576141
_publ_section_title
;
 Tuning optical properties and local lone-pair off-centering in "hollow"
 FA<sub>1-<i>x</i></sub> {<i>en</i>} <sub><i>x</i></sub> Pb
 <sub><i>&#x3b7;</i>-<i>y</i></sub> Sn <sub><i>y</i></sub> Br<sub>3</sub>
 perovskites.
;
_journal_issue                   1
_journal_name_full               'Chemical science'
_journal_page_first              526
_journal_page_last               543
_journal_paper_doi               10.1039/d5sc01841b
_journal_volume                  17
_journal_year                    2026
_chemical_formula_moiety         'Br3 Pb0.5 Sn0.5, 4(C0.25 N0.5)'
_chemical_formula_sum            'C Br3 N2 Pb0.5 Sn0.5'
_chemical_formula_weight         442.70
_space_group_crystal_system      cubic
_space_group_IT_number           221
_space_group_name_Hall           '-P 4 2 3'
_space_group_name_H-M_alt        'P m -3 m'
_atom_sites_solution_primary     dual
_audit_creation_date             2024-10-29
_audit_creation_method
;
Olex2 1.5
(compiled 2023.08.24 svn.re1ec1418 for OlexSys, GUI svn.r6817)
;
_audit_update_record
;
2025-02-21 deposited with the CCDC.	2025-10-21 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            1
_cell_length_a                   5.9617(18)
_cell_length_b                   5.9617(18)
_cell_length_c                   5.9617(18)
_cell_measurement_reflns_used    3787
_cell_measurement_temperature    295
_cell_measurement_theta_max      23.84
_cell_measurement_theta_min      2.69
_cell_volume                     211.89(11)
_computing_molecular_graphics    'Olex2 1.5 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 1.5 (Dolomanov et al., 2009)'
_computing_structure_refinement  'SHELXL 2018/1 (Sheldrick, 2015)'
_computing_structure_solution    'SHELXT 2014/5 (Sheldrick, 2014)'
_diffrn_ambient_temperature      295
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device_type  'STOE STADIVARI'
_diffrn_radiation_type           AgK\a
_diffrn_radiation_wavelength     0.56083
_diffrn_reflns_av_R_equivalents  0.0166
_diffrn_reflns_av_unetI/netI     0.0086
_diffrn_reflns_Laue_measured_fraction_full 1.000
_diffrn_reflns_Laue_measured_fraction_max 1.000
_diffrn_reflns_limit_h_max       7
_diffrn_reflns_limit_h_min       -8
_diffrn_reflns_limit_k_max       8
_diffrn_reflns_limit_k_min       -7
_diffrn_reflns_limit_l_max       7
_diffrn_reflns_limit_l_min       -8
_diffrn_reflns_number            820
_diffrn_reflns_point_group_measured_fraction_full 1.000
_diffrn_reflns_point_group_measured_fraction_max 1.000
_diffrn_reflns_theta_full        19.664
_diffrn_reflns_theta_max         24.879
_diffrn_reflns_theta_min         2.696
_diffrn_source                   'Axo Ag'
_exptl_absorpt_coefficient_mu    13.687
_exptl_absorpt_correction_T_max  0.1972
_exptl_absorpt_correction_T_min  0.1557
_exptl_absorpt_correction_type   empirical
_exptl_absorpt_process_details
;
STOE LANA, absorption correction by scaling of reflection intensities.
J. Koziskova, F. Hahn, J. Richter, J. Kozisek, "Comparison of different
absorption corrections on the model structure of tetrakis(\m~2~-acetato)-
diaqua-di-copper(II)", Acta Chimica Slovaca, vol. 9, no. 2, 2016, pp. 136 - 140.
;
_exptl_crystal_colour            yellow
_exptl_crystal_colour_primary    yellow
_exptl_crystal_density_diffrn    3.469
_exptl_crystal_description       irregular
_exptl_crystal_F_000             191
_exptl_crystal_size_max          0.204
_exptl_crystal_size_mid          0.198
_exptl_crystal_size_min          0.17
_refine_diff_density_max         0.922
_refine_diff_density_min         -0.926
_refine_diff_density_rms         0.249
_refine_ls_extinction_coef       0.056(15)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     'SHELXL-2018/1 (Sheldrick 2018)'
_refine_ls_goodness_of_fit_ref   1.219
_refine_ls_hydrogen_treatment    undef
_refine_ls_matrix_type           full
_refine_ls_number_parameters     9
_refine_ls_number_reflns         105
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.221
_refine_ls_R_factor_all          0.0303
_refine_ls_R_factor_gt           0.0303
_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^)+(0.0581P)^2^] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0829
_refine_ls_wR_factor_ref         0.0829
_reflns_Friedel_coverage         0.000
_reflns_number_gt                105
_reflns_number_total             105
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d5sc01841b2.cif
_cod_data_source_block           full_CCDC2
_cod_depositor_comments
'Adding full bibliography for 1576135--1576153.cif.'
_cod_original_cell_volume        211.89(19)
_cod_original_formula_sum        'C Br3 N2 Pb0.50 Sn0.50'
_cod_database_code               1576141
_shelx_shelxl_version_number     2018/1
_shelx_estimated_absorpt_t_max   0.204
_shelx_estimated_absorpt_t_min   0.167
_olex2_refinement_description
;
1. Shared sites
{Sn, Pb}
2. Restrained distances
 N_$1-C
 1.45 with sigma of 0.02
3. Uiso/Uaniso restraints and constraints
Uanis(Sn) = Uanis(Pb)
4. Others
 Fixed Sof: Sn(0.010417) Pb(0.010417) N(0.041667)
;
_shelx_res_checksum              69512
_olex2_submission_special_instructions 'No special instructions were received'