2,3,4,5,7,7,8,8,-Octafluorobicyclo[4.2.0]octa-1,3,5-triene at 125K
Boese, Roland; Bläser, Dieter; Latz, Rüdiger; Bäumen, Anja; Acta Crystallographica Section C 55 (1999) IUC9900036–; doi:10.1107/S0108270199099606

data_2008408
_publ_section_title
;
 2,3,4,5,7,7,8,8,-Octafluorobicyclo[4.2.0]octa-1,3,5-triene at 125K
;
_journal_issue                   4
_journal_name_full               'Acta Crystallographica Section C'
_journal_page_first              IUC9900036
_journal_paper_doi               10.1107/S0108270199099606
_journal_volume                  55
_journal_year                    1999
_chemical_formula_sum            'C8 F8'
_chemical_formula_weight         248.08
_chemical_name_systematic
;
 perfluoro-benzocyclobutene
;
_space_group_IT_number           88
_symmetry_cell_setting           tetragonal
_symmetry_space_group_name_Hall  '-I 4ad'
_symmetry_space_group_name_H-M   'I 41/a :2'
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            8
_cell_length_a                   8.6226(16)
_cell_length_b                   8.6226(16)
_cell_length_c                   21.730(5)
_cell_measurement_reflns_used    50
_cell_measurement_temperature    125(2)
_cell_measurement_theta_max      25
_cell_measurement_theta_min      20
_cell_volume                     1615.6(6)
_computing_cell_refinement       'P3-VMS  (Siemens 1991)'
_computing_data_collection       'P3-VMS  (Siemens 1991)'
_computing_data_reduction        'XDISK (Siemens, 1991)'
_computing_molecular_graphics    'SHELXL97 (Sheldrick, 1997)'
_computing_publication_material  'SHELXL97 (Sheldrick, 1997)'
_computing_structure_refinement  'SHELXL97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      125(2)
_diffrn_measured_fraction_theta_full 0.352
_diffrn_measured_fraction_theta_max 0.352
_diffrn_measurement_device_type  'Nicolet R3m/V four-circle'
_diffrn_measurement_method       'Wyckoff scan mode'
_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  0.059
_diffrn_reflns_av_sigmaI/netI    0.0433
_diffrn_reflns_limit_h_max       13
_diffrn_reflns_limit_h_min       -15
_diffrn_reflns_limit_k_max       13
_diffrn_reflns_limit_k_min       -4
_diffrn_reflns_limit_l_max       33
_diffrn_reflns_limit_l_min       -34
_diffrn_reflns_number            4330
_diffrn_reflns_theta_full        39.85
_diffrn_reflns_theta_max         39.85
_diffrn_reflns_theta_min         2.54
_diffrn_standards_decay_%        <3
_diffrn_standards_interval_count 100
_diffrn_standards_number         2
_exptl_absorpt_coefficient_mu    0.250
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    2.040
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       cylindrical
_exptl_crystal_F_000             960
_exptl_crystal_size_max          3
_exptl_crystal_size_rad          0.3
_refine_diff_density_max         0.516
_refine_diff_density_min         -0.630
_refine_ls_extinction_coef       0.004(2)
_refine_ls_extinction_method     SHELXL97
_refine_ls_goodness_of_fit_ref   1.075
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     74
_refine_ls_number_reflns         1781
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.075
_refine_ls_R_factor_all          0.074
_refine_ls_R_factor_gt           0.063
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w = 1/[\s^2^(Fo^2^)+(0.0996P)^2^+1.3833P] where P = (Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_ref         0.200
_reflns_number_gt                1412
_reflns_number_total             1781
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            qa0106.cif
_cod_data_source_block           QA0106
_cod_original_sg_symbol_H-M      'I 41/a'
_cod_database_code               2008408