An elusive thermal [2 + 2] cycloaddition driven by visible light photocatalysis: tapping into strain to access C2-symmetric tricyclic rings.
Singh, Kamaljeet; Trinh, Winston; Latifi, Reza; Weaver, Jimmie D.; Organic & biomolecular chemistry 17 (2019) 1854–1861; doi:10.1039/c8ob01273c

data_7156299
_publ_section_title
;
 An elusive thermal [2 + 2] cycloaddition driven by visible light
 photocatalysis: tapping into strain to access C2-symmetric tricyclic
 rings.
;
_journal_issue                   7
_journal_name_full               'Organic &amp; biomolecular chemistry'
_journal_page_first              1854
_journal_page_last               1861
_journal_paper_doi               10.1039/c8ob01273c
_journal_volume                  17
_journal_year                    2019
_chemical_formula_moiety         'C26 H32'
_chemical_formula_sum            'C26 H32'
_chemical_formula_weight         344.51
_chemical_name_systematic
(5aS,5bS)-5a,5b-diphenyltetradecahydrocyclobuta[1,2:3,4]di[7]annulene
_space_group_crystal_system      monoclinic
_space_group_IT_number           14
_space_group_name_Hall           '-P 2yn'
_space_group_name_H-M_alt        'P 1 21/n 1'
_symmetry_space_group_name_Hall  '-P 2yn'
_symmetry_space_group_name_H-M   'P 1 21/n 1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_audit_creation_date             2018-05-01
_audit_creation_method
;
Olex2 1.2
(compiled 2017.01.04 svn.r3372 for OlexSys, GUI svn.r5292)
;
_audit_update_record
;
2018-05-01 deposited with the CCDC.
2018-06-25 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 111.719(2)
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   14.3431(18)
_cell_length_b                   9.3243(12)
_cell_length_c                   15.4742(19)
_cell_measurement_reflns_used    3892
_cell_measurement_temperature    100
_cell_measurement_theta_max      27.35
_cell_measurement_theta_min      2.44
_cell_volume                     1922.6(4)
_computing_cell_refinement       'Bruker SAINT'
_computing_data_collection       'Bruker APEX2'
_computing_data_reduction        'Bruker SAINT'
_computing_molecular_graphics    'Bruker SHELXTL'
_computing_publication_material  'Bruker SHELXTL'
_computing_structure_refinement  'SHELXL-2014 (Sheldrick 2014)'
_computing_structure_solution    'SHELXS-97 (Sheldrick 2008)'
_diffrn_ambient_temperature      100
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_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  0.0791
_diffrn_reflns_av_unetI/netI     0.0520
_diffrn_reflns_Laue_measured_fraction_full 1.000
_diffrn_reflns_Laue_measured_fraction_max 1.000
_diffrn_reflns_limit_h_max       18
_diffrn_reflns_limit_h_min       -18
_diffrn_reflns_limit_k_max       12
_diffrn_reflns_limit_k_min       -12
_diffrn_reflns_limit_l_max       19
_diffrn_reflns_limit_l_min       -20
_diffrn_reflns_number            28560
_diffrn_reflns_point_group_measured_fraction_full 1.000
_diffrn_reflns_point_group_measured_fraction_max 1.000
_diffrn_reflns_theta_full        25.242
_diffrn_reflns_theta_max         27.482
_diffrn_reflns_theta_min         1.655
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.066
_exptl_absorpt_correction_T_max  0.7461
_exptl_absorpt_correction_T_min  0.6444
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
SADABS-2016/2 (Bruker,2016/2) was used for absorption correction.
wR2(int) was 0.0712 before and 0.0621 after correction.
The Ratio of minimum to maximum transmission is 0.8637.
The \l/2 correction factor is Not present.
;
_exptl_crystal_colour            colorless
_exptl_crystal_colour_lustre     clear
_exptl_crystal_colour_modifier   yellowish
_exptl_crystal_colour_primary    yellow
_exptl_crystal_density_diffrn    1.190
_exptl_crystal_description       block
_exptl_crystal_F_000             752
_exptl_crystal_recrystallization_method 'Re-crystallisation from solvent'
_exptl_crystal_size_max          0.185
_exptl_crystal_size_mid          0.136
_exptl_crystal_size_min          0.089
_refine_diff_density_max         0.291
_refine_diff_density_min         -0.210
_refine_diff_density_rms         0.047
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.022
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     235
_refine_ls_number_reflns         4413
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.022
_refine_ls_R_factor_all          0.0778
_refine_ls_R_factor_gt           0.0464
_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^)+(0.0398P)^2^+0.8692P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0975
_refine_ls_wR_factor_ref         0.1116
_reflns_Friedel_coverage         0.000
_reflns_number_gt                3146
_reflns_number_total             4413
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            c8ob01273c2.cif
_cod_data_source_block           kamal_fi_abs_r77
_cod_depositor_comments
'Adding full bibliography for 7156298--7156300.cif.'
_cod_database_code               7156299
_shelx_shelxl_version_number     2014/7
_olex2_refinement_description
;
1. Fixed Uiso
 At 1.2 times of:
  All C(H) groups, All C(H,H) groups
2.a Ternary CH refined with riding coordinates:
 C4(H4), C1(H1)
2.b Secondary CH2 refined with riding coordinates:
 C9(H9A,H9B), C8(H8A,H8B), C7(H7A,H7B), C6(H6A,H6B), C5(H5A,H5B), C20(H20A,
 H20B), C19(H19A,H19B), C18(H18A,H18B), C17(H17A,H17B), C16(H16A,H16B)
2.c Aromatic/amide H refined with riding coordinates:
 C13(H13), C14(H14), C15(H15), C22(H22), C23(H23), C24(H24), C12(H12),
 C11(H11), C25(H25), C26(H26)
;
_shelx_res_checksum              5471
_olex2_submission_special_instructions 'No special instructions were received'