data_2001837 _journal_name_full 'Acta Crystallographica, Section C' _journal_year 1993 _journal_volume C49 _journal_page_first 846 _journal_page_last 848 _publ_section_title ; Structure of Dimethyl 9-Chloro-9,10 -dihydro-9,10-ethenoanthracene-11,12-dicarboxylate ; loop_ _publ_author_name 'Trotter, James' 'Yee, Vivien C.' _chemical_name_systematic ; Dimethyl 9-chloro-9,10-dihydro-9,10-ethenoanthracene-11,12- dicarboxylate ; _chemical_name_common ? _chemical_formula_moiety 'C20 H15 Cl O4' _chemical_formula_sum 'C20 H15 Cl O4' _chemical_formula_structural ? _chemical_formula_analytical ? _chemical_formula_weight 354.79 _chemical_melting_point ? _symmetry_cell_setting monoclinic _symmetry_space_group_name_H-M 'P 21/a ' _symmetry_space_group_name_Hall ? loop_ _symmetry_equiv_pos_as_xyz 'x,y,z' '-x,-y,-z' '1/2+x,1/2-y,z' '1/2-x,1/2+y,-z' _cell_length_a 11.8650(10) _cell_length_b 13.8000(10) _cell_length_c 10.5680(10) _cell_angle_alpha 90.0 _cell_angle_beta 104.250(10) _cell_angle_gamma 90.0 _cell_volume 1677.10(10) _cell_formula_units_Z 4 _cell_measurement_reflns_used 25 _cell_measurement_theta_min 31 _cell_measurement_theta_max 46 _cell_measurement_temperature 294 _exptl_crystal_description prism _exptl_crystal_colour colourless _exptl_crystal_size_max 0.4 _exptl_crystal_size_mid 0.3 _exptl_crystal_size_min 0.2 _exptl_crystal_density_diffrn 1.405 _exptl_crystal_density_meas 1.400 _exptl_crystal_density_method flotation _exptl_crystal_F_000 736 _exptl_absorpt_coefficient_mu 2.22 _exptl_absorpt_correction_type analytical _exptl_absorpt_correction_T_min 0.49 _exptl_absorpt_correction_T_max 0.79 _diffrn_ambient_temperature 294 _diffrn_radiation_type 'Copper K\a' _diffrn_radiation_wavelength 1.54056 _diffrn_radiation_source xray_tube _diffrn_radiation_monochromator graphite _diffrn_measurement_device 'Nonius CAD4-F' _diffrn_reflns_number 3438 _diffrn_reflns_av_R_equivalents ? _diffrn_reflns_av_sigmaI/netI ? _diffrn_reflns_theta_max 75 _diffrn_reflns_limit_h_min -14 _diffrn_reflns_limit_h_max 0 _diffrn_reflns_limit_k_min 0 _diffrn_reflns_limit_k_max 17 _diffrn_reflns_limit_l_min -12 _diffrn_reflns_limit_l_max 13 _diffrn_reflns_reduction_process ? _diffrn_standards_number 3 _diffrn_standards_interval_count 150 _diffrn_standards_interval_time ? _diffrn_standards_decay_% 0 _reflns_number_total 3438 _reflns_number_observed 2291 _reflns_observed_criterion 'I>3\s(I)' _refine_ls_structure_factor_coef F _refine_ls_matrix_type full _refine_ls_R_factor_all .078 _refine_ls_R_factor_obs .046 _refine_ls_wR_factor_all .058 _refine_ls_wR_factor_obs .058 _refine_ls_goodness_of_fit_all ? _refine_ls_goodness_of_fit_obs 2.2 _refine_ls_number_reflns 2291 _refine_ls_number_parameters 287 _refine_ls_number_restraints 0 _refine_ls_number_constraints 0 _refine_ls_hydrogen_treatment 'refall' _refine_ls_weighting_scheme '1/\s^2^(F)' _refine_ls_shift/esd_max '0.31 (H parameter)' _refine_ls_shift/esd_mean .02 _refine_diff_density_max .28 _refine_diff_density_min -.23 _refine_ls_extinction_method Coppens _refine_ls_extinction_coef 108.E2(4) _refine_ls_abs_structure_details ? _refine_ls_abs_structure_Flack ? loop_ _atom_type_symbol _atom_type_description _atom_type_scat_dispersion_real _atom_type_scat_dispersion_imag _atom_type_scat_source C ? .017 .009 'International Tables Vol IV Table 2.3.1' H ? 0 0 'International Tables Vol IV Table 2.3.1' O ? .047 .032 'International Tables Vol IV Table 2.3.1' Cl ? .348 .702 'International Tables Vol IV Table 2.3.1' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv C1 .7172(3) .2652(3) .4032(3) .050 C2 .7971(3) .2980(3) .3359(4) .055 C3 .8798(3) .3658(3) .3915(4) .053 C4 .8845(3) .4029(2) .5153(3) .046 C4a .8059(3) .3708(2) .5821(3) .040 C5 .6386(3) .5316(3) .7278(3) .052 C6 .5197(4) .5525(3) .7008(4) .064 C7 .4385(3) .4845(4) .6474(4) .065 C8 .4717(3) .3918(3) .6189(4) .057 C8a .5899(3) .3693(2) .6450(3) .045 C9 .6425(3) .2758(2) .6137(3) .046 C9a .7218(3) .3020(2) .5262(3) .041 C10 .7959(2) .4013(2) .7180(3) .040 C10a .6720(3) .4396(2) .7001(3) .042 C11 .7245(3) .2414(2) .7406(3) .043 C12 .8045(3) .3065(2) .7973(3) .040 C13 .7163(3) .1383(2) .7785(3) .047 C14 .7883(8) .0155(3) .9288(6) .084 C15 .8929(3) .2950(2) .9235(3) .042 C16 1.0831(4) .2454(6) 1.0227(5) .078 O1 .7857(3) .1167(2) .8929(2) .064 O2 .6558(2) .0815(2) .7087(3) .074 O3 .9916(2) .2603(2) .9054(2) .053 O4 .8764(2) .3170(2) 1.0267(2) .064 Cl .90330(10) .48710(10) .79410(10) .053