Synthesis of highly hindered oxepins and an azepine from bis-trityl carbenium ions: structural characterisation by NMR and X-ray crystallography
Carey, Kieran A.; Clegg, William; Elsegood, Mark R. J.; Golding, Bernard T.; Stuart Hill, M. N.; Maskill, Howard; Journal of the Chemical Society, Perkin Transactions 1  (2002) 2673–; doi:10.1039/b207108h

data_7204499
_publ_section_title
;
 Synthesis of highly hindered oxepins and an azepine from bis-trityl
 carbenium ions: structural characterisation by NMR and X-ray
 crystallography
;
_journal_issue                   23
_journal_name_full
'Journal of the Chemical Society, Perkin Transactions 1'
_journal_page_first              2673
_journal_paper_doi               10.1039/b207108h
_journal_year                    2002
_chemical_formula_sum            'C40 H34 O4'
_chemical_formula_weight         578.67
_space_group_IT_number           14
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-P 2yn'
_symmetry_space_group_name_H-M   'P 1 21/n 1'
_atom_sites_solution_hydrogens   'geom except H1&2 coords freely refined'
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 110.699(18)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   13.017(3)
_cell_length_b                   16.298(6)
_cell_length_c                   15.554(4)
_cell_measurement_reflns_used    36
_cell_measurement_temperature    160(2)
_cell_measurement_theta_max      49.35
_cell_measurement_theta_min      30.91
_cell_volume                     3086.8(16)
_computing_cell_refinement       'Stoe DIF4'
_computing_data_collection       'Stoe DIF4'
_computing_data_reduction        'local programs'
_computing_molecular_graphics    'Siemens SHELXTL'
_computing_publication_material  'SHELXTL and local programs'
_computing_structure_refinement  'Siemens SHELXTL'
_computing_structure_solution    'Siemens SHELXTL'
_diffrn_ambient_temperature      160(2)
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device_type  'Stoe-Siemens diffractometer'
_diffrn_measurement_method       '\w/\q scans with on-line profile fitting'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54184
_diffrn_reflns_av_R_equivalents  0.0861
_diffrn_reflns_av_sigmaI/netI    0.1068
_diffrn_reflns_limit_h_max       13
_diffrn_reflns_limit_h_min       -13
_diffrn_reflns_limit_k_max       17
_diffrn_reflns_limit_k_min       -17
_diffrn_reflns_limit_l_max       16
_diffrn_reflns_limit_l_min       -16
_diffrn_reflns_number            7745
_diffrn_reflns_theta_full        54.99
_diffrn_reflns_theta_max         54.99
_diffrn_reflns_theta_min         3.82
_diffrn_standards_decay_%        2
_diffrn_standards_interval_time  60
_diffrn_standards_number         5
_exptl_absorpt_coefficient_mu    0.626
_exptl_absorpt_correction_T_max  0.920
_exptl_absorpt_correction_T_min  0.613
_exptl_absorpt_correction_type   empirical
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.245
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             1224
_exptl_crystal_size_max          0.38
_exptl_crystal_size_mid          0.38
_exptl_crystal_size_min          0.23
_refine_diff_density_max         0.162
_refine_diff_density_min         -0.237
_refine_diff_density_rms         0.044
_refine_ls_extinction_coef       0.0008(3)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     SHELXL
_refine_ls_goodness_of_fit_ref   1.023
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     469
_refine_ls_number_reflns         3881
_refine_ls_number_restraints     265
_refine_ls_restrained_S_all      1.010
_refine_ls_R_factor_all          0.1856
_refine_ls_R_factor_gt           0.0840
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.1110P)^2^+0.7230P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.2060
_refine_ls_wR_factor_ref         0.2787
_reflns_number_gt                1597
_reflns_number_total             3881
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            b207108h.txt
_cod_data_source_block           hm14
_cod_original_cell_volume        3086.7(15)
_cod_original_sg_symbol_H-M      P2(1)/n
_cod_database_code               7204499