Partial fluorination overcomes herringbone crystal packing in small polycyclic aromatics.
Cho, Don M.; Parkin, Sean R.; Watson, Mark D.; Organic letters 7 (2005) 1067–1068; doi:10.1021/ol050019c

data_1506509
_publ_section_title
;
 Partial fluorination overcomes herringbone crystal packing in small
 polycyclic aromatics.
;
_journal_issue                   6
_journal_name_full               'Organic letters'
_journal_page_first              1067
_journal_page_last               1068
_journal_paper_doi               10.1021/ol050019c
_journal_volume                  7
_journal_year                    2005
_chemical_formula_sum            'C18 H8 F4'
_chemical_formula_weight         300.24
_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
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 95.001(2)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   10.9890(5)
_cell_length_b                   6.7478(3)
_cell_length_c                   16.2987(7)
_cell_measurement_reflns_used    4418
_cell_measurement_temperature    90.0(2)
_cell_measurement_theta_max      68.03
_cell_measurement_theta_min      4.67
_cell_volume                     1203.97(9)
_computing_cell_refinement       'APEX2 (Bruker-Nonius, 2004)'
_computing_data_collection       'APEX2 (Bruker-Nonius, 2004)'
_computing_data_reduction        'APEX2 (Bruker-Nonius, 2004)'
_computing_molecular_graphics    'XP in SHELXTL (Sheldrick, 1994)'
_computing_publication_material
; 
SHELX97-2 (Sheldrick, 1997) and local procedures 
;
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      90.0(2)
_diffrn_detector_area_resol_mean 18
_diffrn_measured_fraction_theta_full .980
_diffrn_measured_fraction_theta_max .980
_diffrn_measurement_device_type  'Bruker-Nonius X8 Proteum'
_diffrn_measurement_method       '\w and \f scans'
_diffrn_radiation_monochromator  'graded multilayer optics'
_diffrn_radiation_source         'fine-focus rotating anode'
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54178
_diffrn_reflns_av_R_equivalents  0.0471
_diffrn_reflns_av_sigmaI/netI    0.0405
_diffrn_reflns_limit_h_max       13
_diffrn_reflns_limit_h_min       -13
_diffrn_reflns_limit_k_max       8
_diffrn_reflns_limit_k_min       -7
_diffrn_reflns_limit_l_max       19
_diffrn_reflns_limit_l_min       -19
_diffrn_reflns_number            11981
_diffrn_reflns_theta_full        68.11
_diffrn_reflns_theta_max         68.11
_diffrn_reflns_theta_min         4.67
_exptl_absorpt_coefficient_mu    1.201
_exptl_absorpt_correction_T_max  0.9706
_exptl_absorpt_correction_T_min  0.8245
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'SADABS in APEX2 (Bruker-Nonius, 2004)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.656
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       'thin plate'
_exptl_crystal_F_000             608
_exptl_crystal_size_max          0.35
_exptl_crystal_size_mid          0.20
_exptl_crystal_size_min          0.03
_refine_diff_density_max         .200
_refine_diff_density_min         -.269
_refine_diff_density_rms         .067
_refine_ls_extinction_coef       0.0019(4)
_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   1.027
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     200
_refine_ls_number_reflns         2159
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.027
_refine_ls_R_factor_all          0.0404
_refine_ls_R_factor_gt           0.0362
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0629P)^2^+0.2958P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1014
_refine_ls_wR_factor_ref         0.1059
_reflns_number_gt                1915
_reflns_number_total             2159
_reflns_threshold_expression     >2\s(I)
_cod_data_source_file            ol050019csi20050106_103707.cif
_cod_data_source_block           3
_cod_original_sg_symbol_H-M      'P 21/n'
_cod_database_code               1506509