Synthesis and Study of 7,12,17-Trioxa[11]helicene.
Shyam Sundar, M.; Bedekar, Ashutosh V.; Organic letters 17 (2015) 5808–5811; doi:10.1021/acs.orglett.5b02948

data_1555435
_publ_section_title
;
 Synthesis and Study of 7,12,17-Trioxa[11]helicene.
;
_journal_issue                   23
_journal_name_full               'Organic letters'
_journal_page_first              5808
_journal_page_last               5811
_journal_paper_doi               10.1021/acs.orglett.5b02948
_journal_volume                  17
_journal_year                    2015
_chemical_formula_moiety         'C22 H16 O4'
_chemical_formula_sum            'C22 H16 O4'
_chemical_formula_weight         344.35
_space_group_IT_number           33
_space_group_name_Hall           'P 2c -2n'
_space_group_name_H-M_alt        'P n a 21'
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_H-M   'P n a 21'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            8
_cell_length_a                   23.0883(10)
_cell_length_b                   8.2485(4)
_cell_length_c                   17.6035(8)
_cell_measurement_temperature    293(2)
_cell_volume                     3352.5(3)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_device_type  'Xcalibur, Eos, Gemini'
_diffrn_measurement_method       '\w scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0318
_diffrn_reflns_av_sigmaI/netI    0.0390
_diffrn_reflns_limit_h_max       30
_diffrn_reflns_limit_h_min       -29
_diffrn_reflns_limit_k_max       10
_diffrn_reflns_limit_k_min       -11
_diffrn_reflns_limit_l_max       23
_diffrn_reflns_limit_l_min       -23
_diffrn_reflns_number            19835
_diffrn_reflns_theta_full        29.03
_diffrn_reflns_theta_max         29.03
_diffrn_reflns_theta_min         3.25
_exptl_absorpt_coefficient_mu    0.094
_exptl_crystal_colour            orange
_exptl_crystal_density_diffrn    1.303
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       plate
_exptl_crystal_F_000             1440
_exptl_crystal_size_max          0.29
_exptl_crystal_size_mid          0.26
_exptl_crystal_size_min          0.21
_refine_diff_density_max         0.174
_refine_diff_density_min         -0.171
_refine_diff_density_rms         0.031
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.3(9)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.034
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     473
_refine_ls_number_reflns         7464
_refine_ls_number_restraints     37
_refine_ls_restrained_S_all      1.034
_refine_ls_R_factor_all          0.0788
_refine_ls_R_factor_gt           0.0533
_refine_ls_shift/su_max          0.042
_refine_ls_shift/su_mean         0.001
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0427P)^2^+0.6152P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1055
_refine_ls_wR_factor_ref         0.1179
_reflns_number_gt                5527
_reflns_number_total             8951
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ol5b02948_si_001.cif
_cod_data_source_block           exp_434
_cod_database_code               1555435