# Supplementary Material (ESI) for ChemComm # This journal is © The Royal Society of Chemistry 2000 # CCDC Number: 182/1832 data_1 _audit_creation_method SHELXL-97 _chemical_name_systematic ; ? ; _chemical_name_common pyxophane _chemical_melting_point 265-266 _chemical_formula_moiety 'C20 H16 O4' _chemical_formula_sum 'C20 H16 O4' _chemical_formula_weight 320.33 loop_ _atom_type_symbol _atom_type_description _atom_type_scat_dispersion_real _atom_type_scat_dispersion_imag _atom_type_scat_source 'C' 'C' 0.0181 0.0091 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'H' 'H' 0.0000 0.0000 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' 'O' 'O' 0.0492 0.0322 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' _symmetry_cell_setting Monoclinic _symmetry_space_group_name_H-M P21/c loop_ _symmetry_equiv_pos_as_xyz 'x, y, z' '-x, y+1/2, -z+1/2' '-x, -y, -z' 'x, -y-1/2, z-1/2' _cell_length_a 9.7819(19) _cell_length_b 10.582(3) _cell_length_c 7.8500(16) _cell_angle_alpha 90.00 _cell_angle_beta 109.810(15) _cell_angle_gamma 90.00 _cell_volume 764.5(3) _cell_formula_units_Z 2 _cell_measurement_temperature 298(2) _cell_measurement_reflns_used ? _cell_measurement_theta_min ? _cell_measurement_theta_max ? _exptl_crystal_description ? _exptl_crystal_colour ? _exptl_crystal_size_max 0.30 _exptl_crystal_size_mid 0.25 _exptl_crystal_size_min 0.20 _exptl_crystal_density_meas ? _exptl_crystal_density_diffrn 1.392 _exptl_crystal_density_method 'not measured' _exptl_crystal_F_000 336 _exptl_absorpt_coefficient_mu 0.791 _exptl_absorpt_correction_type ? _exptl_absorpt_correction_T_min 0.7972 _exptl_absorpt_correction_T_max 0.8578 _exptl_absorpt_process_details ? _exptl_special_details ; ? ; _diffrn_ambient_temperature 298(2) _diffrn_radiation_wavelength 1.54180 _diffrn_radiation_type CuK\a _diffrn_radiation_source 'fine-focus sealed tube' _diffrn_radiation_monochromator graphite _diffrn_measurement_device_type ? _diffrn_measurement_method ? _diffrn_detector_area_resol_mean ? _diffrn_standards_number ? _diffrn_standards_interval_count ? _diffrn_standards_interval_time ? _diffrn_standards_decay_% ? _diffrn_reflns_number 1806 _diffrn_reflns_av_R_equivalents 0.0512 _diffrn_reflns_av_sigmaI/netI 0.0552 _diffrn_reflns_limit_h_min -11 _diffrn_reflns_limit_h_max 11 _diffrn_reflns_limit_k_min -1 _diffrn_reflns_limit_k_max 12 _diffrn_reflns_limit_l_min -1 _diffrn_reflns_limit_l_max 9 _diffrn_reflns_theta_min 4.81 _diffrn_reflns_theta_max 67.37 _reflns_number_total 1300 _reflns_number_gt 811 _reflns_threshold_expression >2sigma(I) _computing_data_collection ? _computing_cell_refinement ? _computing_data_reduction ? _computing_structure_solution 'SHELXS-97 (Sheldrick, 1990)' _computing_structure_refinement 'SHELXL-97 (Sheldrick, 1997)' _computing_molecular_graphics ? _computing_publication_material ? _refine_special_details ; Refinement of F^2^ against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F^2^, conventional R-factors R are based on F, with F set to zero for negative F^2^. The threshold expression of F^2^ > 2sigma(F^2^) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F^2^ are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger. ; _refine_ls_structure_factor_coef Fsqd _refine_ls_matrix_type full _refine_ls_weighting_scheme calc _refine_ls_weighting_details 'calc w=1/[\s^2^(Fo^2^)+(0.0818P)^2^+0.0562P] where P=(Fo^2^+2Fc^2^)/3' _atom_sites_solution_primary direct _atom_sites_solution_secondary difmap _atom_sites_solution_hydrogens geom _refine_ls_hydrogen_treatment mixed _refine_ls_extinction_method SHELXL _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_number_reflns 1300 _refine_ls_number_parameters 110 _refine_ls_number_restraints 0 _refine_ls_R_factor_all 0.0772 _refine_ls_R_factor_gt 0.0460 _refine_ls_wR_factor_ref 0.1558 _refine_ls_wR_factor_gt 0.1235 _refine_ls_goodness_of_fit_ref 1.015 _refine_ls_restrained_S_all 1.015 _refine_ls_shift/su_max 0.056 _refine_ls_shift/su_mean 0.004 loop_ _atom_site_label _atom_site_type_symbol _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv _atom_site_adp_type _atom_site_occupancy _atom_site_symmetry_multiplicity _atom_site_calc_flag _atom_site_refinement_flags _atom_site_disorder_assembly _atom_site_disorder_group O1 O 0.6091(2) 0.30967(17) 0.1282(2) 0.0643(6) Uani 1 1 d . . . O2 O 0.08783(19) 0.4473(2) 0.2057(2) 0.0661(6) Uani 1 1 d . . . C3 C 0.4839(3) 0.3529(2) 0.1543(3) 0.0500(6) Uani 1 1 d . . . C4 C 0.3424(3) 0.4997(2) 0.2580(3) 0.0476(6) Uani 1 1 d . . . H4 H 0.3357 0.5754 0.3148 0.057 Uiso 1 1 calc R . . C5 C 0.2221(3) 0.4218(2) 0.1927(3) 0.0497(7) Uani 1 1 d . . . C6 C 0.4725(3) 0.4646(2) 0.2385(3) 0.0487(6) Uani 1 1 d . . . H6 H 0.5531 0.5171 0.2827 0.058 Uiso 1 1 calc R . . C7 C 0.2339(3) 0.3092(2) 0.1068(3) 0.0573(7) Uani 1 1 d . . . H7 H 0.1536 0.2563 0.0626 0.069 Uiso 1 1 calc R . . C8 C 0.1969(3) 0.5991(3) 0.6215(4) 0.0569(7) Uani 1 1 d . . . C9 C 0.3634(3) 0.2759(2) 0.0869(3) 0.0564(7) Uani 1 1 d . . . H9 H 0.3701 0.2011 0.0279 0.068 Uiso 1 1 calc R . . C10 C 0.1381(3) 0.5872(3) 0.4638(3) 0.0596(8) Uani 1 1 d . . . C11 C 0.0670(3) 0.5699(3) 0.2678(3) 0.0619(8) Uani 1 1 d . . . H11A H -0.0363 0.5851 0.2371 0.074 Uiso 1 1 calc R . . H11B H 0.1046 0.6324 0.2047 0.074 Uiso 1 1 calc R . . C12 C 0.7326(3) 0.3915(3) 0.1816(3) 0.0615(8) Uani 1 1 d . . . H12A H 0.7024 0.4753 0.1332 0.074 Uiso 1 1 calc R . . H12B H 0.8029 0.3609 0.1290 0.074 Uiso 1 1 calc R . . loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_23 _atom_site_aniso_U_13 _atom_site_aniso_U_12 O1 0.0789(13) 0.0586(12) 0.0527(12) -0.0061(9) 0.0187(9) 0.0121(10) O2 0.0589(11) 0.0817(14) 0.0516(11) 0.0005(10) 0.0109(9) -0.0092(10) C3 0.0671(15) 0.0465(14) 0.0298(12) 0.0026(11) 0.0078(11) 0.0045(12) C4 0.0601(14) 0.0443(13) 0.0332(12) -0.0023(11) 0.0093(10) -0.0038(11) C5 0.0539(14) 0.0576(16) 0.0299(11) 0.0074(12) 0.0042(10) -0.0040(11) C6 0.0586(14) 0.0477(14) 0.0345(12) -0.0010(11) 0.0091(10) -0.0025(11) C7 0.0718(17) 0.0499(16) 0.0334(13) 0.0030(12) -0.0042(12) -0.0160(13) C8 0.0581(14) 0.0656(18) 0.0485(15) 0.0094(14) 0.0200(12) 0.0108(13) C9 0.0802(18) 0.0400(13) 0.0343(13) -0.0027(12) 0.0004(12) -0.0004(13) C10 0.0550(14) 0.0766(19) 0.0471(15) 0.0122(15) 0.0174(12) 0.0079(13) C11 0.0523(15) 0.084(2) 0.0442(14) 0.0103(15) 0.0098(11) 0.0041(13) C12 0.0681(16) 0.0740(19) 0.0437(14) 0.0046(14) 0.0207(12) 0.0108(15) _geom_special_details ; All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. ; loop_ _geom_bond_atom_site_label_1 _geom_bond_atom_site_label_2 _geom_bond_distance _geom_bond_site_symmetry_2 _geom_bond_publ_flag O1 C3 1.386(3) . ? O1 C12 1.429(3) . ? O2 C5 1.378(3) . ? O2 C11 1.425(3) . ? C3 C6 1.378(3) . ? C3 C9 1.382(3) . ? C4 C6 1.383(3) . ? C4 C5 1.385(3) . ? C5 C7 1.393(3) . ? C7 C9 1.374(4) . ? C8 C10 1.182(3) . ? C8 C12 1.467(3) 3_666 ? C10 C11 1.469(3) . ? C12 C8 1.467(3) 3_666 ? loop_ _geom_angle_atom_site_label_1 _geom_angle_atom_site_label_2 _geom_angle_atom_site_label_3 _geom_angle _geom_angle_site_symmetry_1 _geom_angle_site_symmetry_3 _geom_angle_publ_flag C3 O1 C12 117.3(2) . . ? C5 O2 C11 117.0(2) . . ? C6 C3 C9 119.5(2) . . ? C6 C3 O1 125.0(2) . . ? C9 C3 O1 115.5(2) . . ? C6 C4 C5 119.8(2) . . ? O2 C5 C4 124.6(2) . . ? O2 C5 C7 116.1(2) . . ? C4 C5 C7 119.3(2) . . ? C3 C6 C4 120.7(2) . . ? C9 C7 C5 120.3(2) . . ? C10 C8 C12 177.6(3) . 3_666 ? C7 C9 C3 120.3(2) . . ? C8 C10 C11 178.7(3) . . ? O2 C11 C10 113.6(2) . . ? O1 C12 C8 113.5(2) . 3_666 ? _diffrn_measured_fraction_theta_max 0.941 _diffrn_reflns_theta_full 67.37 _diffrn_measured_fraction_theta_full 0.941 _refine_diff_density_max 0.159 _refine_diff_density_min -0.147 _refine_diff_density_rms 0.044