Pyxophanes: selective gas phase ion complexation by 1,6,13,18-tetraoxa[6.6]paracyclophane-3,15-diyne
Behm, Robert; Gokel, George W.; Gloeckner, Charles; Grayson, Michael A.; Gross, Michael L.; Chemical Communications  (2000) 2377–; doi:10.1039/b005443g

data_7111056
_publ_section_title
;
 Pyxophanes: selective gas phase ion complexation by
 1,6,13,18-tetraoxa[6.6]paracyclophane-3,15-diyne
;
_journal_issue                   23
_journal_name_full               'Chemical Communications'
_journal_page_first              2377
_journal_paper_doi               10.1039/b005443g
_journal_year                    2000
_chemical_formula_moiety         'C20 H16 O4'
_chemical_formula_sum            'C20 H16 O4'
_chemical_formula_weight         320.33
_chemical_melting_point          265.5(5)
_chemical_name_common            pyxophane
_space_group_IT_number           14
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-P 2ybc'
_symmetry_space_group_name_H-M   'P 1 21/c 1'
_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                 109.810(15)
_cell_angle_gamma                90.00
_cell_formula_units_Z            2
_cell_length_a                   9.7819(19)
_cell_length_b                   10.582(3)
_cell_length_c                   7.8500(16)
_cell_measurement_temperature    298(2)
_cell_volume                     764.5(3)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      298(2)
_diffrn_measured_fraction_theta_full 0.941
_diffrn_measured_fraction_theta_max 0.941
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54180
_diffrn_reflns_av_R_equivalents  0.0512
_diffrn_reflns_av_sigmaI/netI    0.0552
_diffrn_reflns_limit_h_max       11
_diffrn_reflns_limit_h_min       -11
_diffrn_reflns_limit_k_max       12
_diffrn_reflns_limit_k_min       -1
_diffrn_reflns_limit_l_max       9
_diffrn_reflns_limit_l_min       -1
_diffrn_reflns_number            1806
_diffrn_reflns_theta_full        67.37
_diffrn_reflns_theta_max         67.37
_diffrn_reflns_theta_min         4.81
_exptl_absorpt_coefficient_mu    0.791
_exptl_absorpt_correction_T_max  0.8578
_exptl_absorpt_correction_T_min  0.7972
_exptl_crystal_density_diffrn    1.392
_exptl_crystal_density_method    'not measured'
_exptl_crystal_F_000             336
_exptl_crystal_size_max          0.30
_exptl_crystal_size_mid          0.25
_exptl_crystal_size_min          0.20
_refine_diff_density_max         0.159
_refine_diff_density_min         -0.147
_refine_diff_density_rms         0.044
_refine_ls_extinction_coef       0.014(2)
_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   1.015
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     110
_refine_ls_number_reflns         1300
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.015
_refine_ls_R_factor_all          0.0772
_refine_ls_R_factor_gt           0.0460
_refine_ls_shift/su_max          0.056
_refine_ls_shift/su_mean         0.004
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0818P)^2^+0.0562P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1235
_refine_ls_wR_factor_ref         0.1558
_reflns_number_gt                811
_reflns_number_total             1300
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            b005443gsup1.cif
_cod_data_source_block           1
_cod_depositor_comments
;
The following automatic conversions were performed:

'_chemical_melting_point' value '265-266' was changed to '265.5(5)' -
the average value was taken and precision was
estimated.

'_symmetry_cell_setting' value 'Monoclinic' changed to
'monoclinic' according to
/home/saulius/struct/CIF-dictionaries/cif_core.dic dictionary named
'cif_core.dic' version 2.4.2 from 2011-04-26.

Automatic conversion script
Id: cif_fix_values 1891 2012-01-12 08:04:46Z andrius 
;
_cod_original_sg_symbol_H-M      P21/c
_cod_database_code               7111056