Experimental and spectroscopic evidence of the hidden triplet transition state of quinone methide: a new reactivity paradigm.
Tiwari, Shashikant; Sharma, Ritika; Rawat, Diwan S.; Chemical communications (Cambridge, England) 62 (2026) 2343–2347; doi:10.1039/d5cc06672g

data_7135534
_publ_section_title
;
 Experimental and spectroscopic evidence of the hidden triplet transition
 state of quinone methide: a new reactivity paradigm.
;
_journal_issue                   7
_journal_name_full               'Chemical communications (Cambridge, England)'
_journal_page_first              2343
_journal_page_last               2347
_journal_paper_doi               10.1039/d5cc06672g
_journal_volume                  62
_journal_year                    2026
_chemical_formula_moiety         'C20 H24.75 Cl N O'
_chemical_formula_sum            'C20 H24.75 Cl N O'
_chemical_formula_weight         330.61
_space_group_crystal_system      monoclinic
_space_group_IT_number           14
_space_group_name_Hall           '-P 2ybc'
_space_group_name_H-M_alt        'P 1 21/c 1'
_atom_sites_solution_hydrogens   mixed
_atom_sites_solution_primary     dual
_audit_creation_date             2025-08-19
_audit_creation_method
;
Olex2 1.3
(compiled 2020.11.12 svn.r5f609507 for OlexSys, GUI svn.r6408)
;
_audit_update_record
;
2025-08-19 deposited with the CCDC.	2025-12-22 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 112.781(5)
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   14.7585(6)
_cell_length_b                   10.9981(4)
_cell_length_c                   11.9327(6)
_cell_measurement_reflns_used    9589
_cell_measurement_temperature    150.00(10)
_cell_measurement_theta_max      30.7290
_cell_measurement_theta_min      2.3600
_cell_volume                     1785.77(15)
_computing_cell_refinement       'CrysAlisPro 1.171.43.106a (Rigaku OD, 2024)'
_computing_data_collection       'CrysAlisPro 1.171.43.106a (Rigaku OD, 2024)'
_computing_data_reduction        'CrysAlisPro 1.171.43.106a (Rigaku OD, 2024)'
_computing_molecular_graphics    'Olex2 1.3 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 1.3 (Dolomanov et al., 2009)'
_computing_structure_refinement  'SHELXL 2016/4 (Sheldrick, 2015)'
_computing_structure_solution    'SHELXT 2014/5 (Sheldrick, 2014)'
_diffrn_ambient_environment      N~2~
_diffrn_ambient_temperature      150.00(10)
_diffrn_detector                 'Hybrid Pixel Array Detector'
_diffrn_detector_area_resol_mean 10.0000
_diffrn_detector_type            HyPix
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.999
_diffrn_measurement_details
;
List of Runs (angles in degrees, time in seconds):

  # Type    Start    End  Width  t~exp~   \w     \q     \k     \f   Frames
  1  \w    -18.00  68.00   0.50    2.05    --   -4.75  38.00 -56.00  172
  2  \w      2.00  27.00   0.50    2.05    --   -4.75 -99.00 -60.00   50
  3  \w    -21.00  13.00   0.50    2.05    --   -4.75 -99.00  90.00   68
  4  \w    -78.00   9.00   0.50    2.05    --   -4.75 -38.00 148.00  174
;
_diffrn_measurement_device       'four-circle diffractometer'
_diffrn_measurement_device_type
'XtaLAB Synergy, Single source at home/near, HyPix'
_diffrn_measurement_method       '\w scans'
_diffrn_orient_matrix_type
'CrysAlisPro convention (1999,Acta A55,543-557)'
_diffrn_orient_matrix_UB_11      0.0439220000
_diffrn_orient_matrix_UB_12      0.0214745000
_diffrn_orient_matrix_UB_13      -0.0041199000
_diffrn_orient_matrix_UB_21      -0.0274597000
_diffrn_orient_matrix_UB_22      0.0223469000
_diffrn_orient_matrix_UB_23      -0.0593024000
_diffrn_orient_matrix_UB_31      -0.0058074000
_diffrn_orient_matrix_UB_32      0.0565673000
_diffrn_orient_matrix_UB_33      0.0249696000
_diffrn_radiation_monochromator  mirror
_diffrn_radiation_probe          x-ray
_diffrn_radiation_type           'Mo K\a'
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0285
_diffrn_reflns_av_unetI/netI     0.0292
_diffrn_reflns_Laue_measured_fraction_full 0.999
_diffrn_reflns_Laue_measured_fraction_max 0.999
_diffrn_reflns_limit_h_max       17
_diffrn_reflns_limit_h_min       -15
_diffrn_reflns_limit_k_max       11
_diffrn_reflns_limit_k_min       -12
_diffrn_reflns_limit_l_max       13
_diffrn_reflns_limit_l_min       -14
_diffrn_reflns_number            11459
_diffrn_reflns_point_group_measured_fraction_full 0.999
_diffrn_reflns_point_group_measured_fraction_max 0.999
_diffrn_reflns_theta_full        24.711
_diffrn_reflns_theta_max         24.711
_diffrn_reflns_theta_min         2.381
_diffrn_source                   'micro-focus sealed X-ray tube'
_diffrn_source_type              'PhotonJet (Mo) X-ray Source'
_exptl_absorpt_coefficient_mu    0.219
_exptl_absorpt_correction_T_max  1.00000
_exptl_absorpt_correction_T_min  0.37950
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
CrysAlisPro 1.171.43.106a (Rigaku Oxford Diffraction, 2024)
Empirical absorption correction using spherical harmonics,
implemented in SCALE3 ABSPACK scaling algorithm.
;
_exptl_crystal_colour            'clear whiteish red'
_exptl_crystal_colour_lustre     clear
_exptl_crystal_colour_modifier   whiteish
_exptl_crystal_colour_primary    red
_exptl_crystal_density_diffrn    1.230
_exptl_crystal_description       block
_exptl_crystal_F_000             707
_refine_diff_density_max         0.274
_refine_diff_density_min         -0.342
_refine_diff_density_rms         0.043
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.088
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     224
_refine_ls_number_reflns         3037
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.088
_refine_ls_R_factor_all          0.0397
_refine_ls_R_factor_gt           0.0354
_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^)+(0.0453P)^2^+0.6069P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0921
_refine_ls_wR_factor_ref         0.0950
_reflns_Friedel_coverage         0.000
_reflns_number_gt                2703
_reflns_number_total             3037
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d5cc06672g2.cif
_cod_data_source_block           rs-13l_auto
_cod_original_sg_symbol_H-M      'P 21/c'
_cod_database_code               7135534
_shelx_shelxl_version_number     2016/4
_chemical_oxdiff_formula         'C H N O Cl Br'
_reflns_odcompleteness_completeness 99.95
_reflns_odcompleteness_iscentric 1
_reflns_odcompleteness_theta     26.32
_olex2_refinement_description
;
1. Fixed Uiso
 At 1.2 times of:
  All C(H) groups
 At 1.5 times of:
  All C(H,H) groups, All C(H,H,H) groups, All O(H) groups
2. Others
 Fixed Sof: H002(0.75)
3.a Ternary CH refined with riding coordinates:
 C00C(H00C)
3.b Aromatic/amide H refined with riding coordinates:
 C004(H004), C008(H008), C009(H009), C00B(H00B), C00G(H00G)
3.c Idealised Me refined as rotating group:
 C00I(H00A,H00D,H00E), C00J(H00F,H00H,H00I), C00L(H00M,H00N,H00O), C00M(H00P,
 H00Q,H00R), C00N(H00S,H00T,H00U)
3.d Idealised tetrahedral OH refined as rotating group:
 O002(H002)
;
_shelx_res_checksum              9078
_olex2_submission_special_instructions 'No special instructions were received'
_oxdiff_exptl_absorpt_empirical_details
;
Empirical correction (ABSPACK) includes:
- Absorption correction using spherical harmonics
- Frame scaling
;
_oxdiff_exptl_absorpt_empirical_full_max 1.870
_oxdiff_exptl_absorpt_empirical_full_min 0.422