# Supplementary Material (ESI) for Perkin Transactions # This journal is © The Royal Society of Chemistry 2000 # CCDC Number: 207/415 # CIF Copied by cif2cif, version 0.0.8 - beta ( 2 Apr 98) data_global _audit_creation_method 'maXus' _publ_contact_author_name 'Dr Alison Edwards ' _publ_contact_author_address ; Research School of Chemistry Australian National University A.C.T. 0200 Australia ; _publ_contact_author_email 'ajed@rsc.anu.edu.au ' _publ_contact_author_fax 'australia + 2 6249 0750 ' _publ_contact_author_phone 'australia + 2 62494109 ' _publ_section_title ; ; _publ_section_abstract ; ; _publ_section_comment ; ; _publ_section_synopsis ; ; _publ_section_exptl_prep ; ; _publ_section_exptl_refinement ; Structure solution and refinement: The structure was solved by direct methods(SIR-92) and expanded using Fourier techniques(maXus). Non-hydrogen atoms were refined anisotropically. Hydrogen atoms were included at calculated positions and allowed to ride on the non-hydrogen atom of attachment, except for the hydrogen bonded to nitrogen which was included in its observed location and allowed to ride similarly. The final cycle of full-matrix least squares refinement was based on 1610 observed reflections (I > 3.0sigma(I)) and 208 variable parameters. The maximum and minimum peaks on the final difference Fourier map correspond to 0.17 and -0.19 e A-3, respectively. Structure expansion, refinement and reporting employed the Maxus crystallographic software ; _publ_section_figure_captions ; ; _publ_section_acknowledgements ; ; _diffrn_measurement_device 'KappaCCD' _computing_data_collection 'KappaCCD' _diffrn_measurement_method '2o omega frames' _computing_data_reduction 'Denzo and Scalepak (Otwinowski & Minor, 1997)' _diffrn_radiation_source 'fine-focus sealed tube' _diffrn_radiation_monochromator graphite _diffrn_reflns_limit_h_min -12 _diffrn_reflns_limit_h_max 12 _diffrn_reflns_limit_k_min -15 _diffrn_reflns_limit_k_max 15 _diffrn_reflns_limit_l_min -15 _diffrn_reflns_limit_l_max 15 loop_ _diffrn_radiation_wavelength 0.71073 _diffrn_radiation_wavelength_id all _cell_formula_units_Z 4 _exptl_crystal_density_diffrn 1.324 _exptl_crystal_density_method 'not measured' _exptl_special_details ; ; _chemical_formula_weight 308.381 _diffrn_radiation_type ' MoK\a' loop_ _symmetry_equiv_pos_as_xyz '+X,+Y,+Z' '-X,-Y,-Z' '-X+ 1/2,+Y+ 1/2,-Z+ 1/2' '+X+ 1/2,-Y+ 1/2,+Z+ 1/2' _symmetry_space_group_name_H-M 'P 21/n ' _symmetry_cell_setting 'Monoclinic' _chemical_formula_moiety 'C19 H20 N2 O2 ' _chemical_formula_sum 'C19 H20 N2 O2 ' _chemical_name_systematic ; ; _cell_length_a 10.040(1) _cell_length_b 12.331(1) _cell_length_c 12.675(1) _cell_angle_alpha 90.00 _cell_angle_beta 99.651(7) _cell_angle_gamma 90.00 _cell_volume 1547.0(3) _diffrn_reflns_number 5401 _diffrn_reflns_theta_max 26.01 _diffrn_reflns_av_R_equivalents 0.055 _cell_measurement_reflns_used 5217 _cell_measurement_theta_min 2.910 _cell_measurement_theta_max 26.022 _chemical_compound_source 'Local laboratory' _exptl_crystal_description 'Plate' _exptl_crystal_colour 'Colourless' _cell_measurement_temperature 200 _refine_ls_hydrogen_treatment 'mixed' # Submission details _publ_requested_journal '' _computing_structure_solution 'SIR92 (Altomare et al., 1994)' _atom_sites_solution_primary direct _atom_sites_solution_secondary difmap _exptl_absorpt_correction_type none _exptl_absorpt_correction_T_min ? _exptl_absorpt_correction_T_max ? _exptl_absorpt_coefficient_mu 0.087 _exptl_crystal_F_000 656 _exptl_crystal_size_min 0.035 _exptl_crystal_size_mid 0.18 _exptl_crystal_size_max 0.55 loop_ _atom_type_symbol _atom_type_description _atom_type_scat_dispersion_real _atom_type_scat_dispersion_imag _atom_type_scat_source 'C ' 'C ' 0.0033 0.0016 'Waasmaier & Kirfel, 1995' 'H ' 'H ' 0.0000 0.0000 'Waasmaier & Kirfel, 1995' 'N ' 'N ' 0.0061 0.0033 'Waasmaier & Kirfel, 1995' 'O ' 'O ' 0.0106 0.0060 'Waasmaier & Kirfel, 1995' _reflns_number_total 3045 _reflns_number_gt 1610 _reflns_threshold_expression 'I> 3.00 sigma(I)' _reflns_d_resolution_low 1.87 _reflns_d_resolution_high 0.64 _reflns_limit_h_max 12 _reflns_limit_h_min 0 _reflns_limit_k_max 15 _reflns_limit_k_min 0 _reflns_limit_l_max 12 _reflns_limit_l_min -12 _refine_ls_matrix_type full _refine_ls_R_factor_all 0.117 _refine_ls_wR_factor_all 0.064 _refine_ls_R_factor_gt 0.048 _refine_ls_wR_factor_gt 0.050 _refine_ls_wR_factor_ref 0.051 _refine_ls_goodness_of_fit_gt 1.150 _refine_ls_goodness_of_fit_ref 1.150 _refine_ls_goodness_of_fit_all 1.393 _refine_ls_number_parameters 208 _refine_ls_number_reflns 1610 _refine_ls_shift/su_max 0.002 _refine_ls_shift/su_mean 0.000 _refine_ls_structure_factor_coef F _refine_ls_weighting_scheme sigma _refine_ls_weighting_details 'w = 1 / ( s^2^(Fo^2^) + 0.03000 * Fo^2^)' _refine_ls_extinction_method none _refine_ls_extinction_coef ? _computing_structure_refinement 'maxus(Mackay et al., 1999)' _computing_molecular_graphics 'Ortep (Johnson, 1976)' _computing_publication_material 'maxus(Mackay et al., 1999)' _atom_sites_solution_hydrogens 'mixed' _refine_diff_density_max 0.17 _refine_diff_density_min -0.19 _refine_diff_density_rms 0.04 #================================================== # ATOMIC COORDINATES AND THERMAL PARAMETERS loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv _atom_site_occupancy _atom_site_adp_type O1 0.8300(2) 0.50410(10) 1.02960(10) 0.0580(10) 1.00 Uij O2 0.5194(2) -0.00480(10) 0.84510(10) 0.0620(10) 1.00 Uij N1 0.9880(2) 0.3783(2) 1.08600(10) 0.0470(10) 1.00 Uij N8 0.6335(2) 0.16740(10) 1.00550(10) 0.0370(10) 1.00 Uij C2 0.8707(2) 0.4292(2) 1.0922(2) 0.0420(10) 1.00 Uij C3 0.7938(2) 0.3943(2) 1.1789(2) 0.0420(10) 1.00 Uij C4 0.6816(2) 0.3100(2) 1.1462(2) 0.0400(10) 1.00 Uij C5 0.5554(3) 0.3645(2) 1.0841(2) 0.0520(10) 1.00 Uij C6 0.4464(3) 0.2832(2) 1.0400(2) 0.0550(10) 1.00 Uij C7 0.4961(2) 0.2044(2) 0.9641(2) 0.0440(10) 1.00 Uij C9 0.6961(2) 0.0786(2) 0.9679(2) 0.0390(10) 1.00 Uij C10 0.8280(2) 0.0788(2) 1.0182(2) 0.0440(10) 1.00 Uij C11 0.8500(2) 0.1681(2) 1.0869(2) 0.0380(10) 1.00 Uij C12 0.9791(2) 0.1937(2) 1.1569(2) 0.0390(10) 1.00 Uij C13 1.0429(2) 0.1139(2) 1.2262(2) 0.0460(10) 1.00 Uij C14 1.1679(3) 0.1294(2) 1.2877(2) 0.0490(10) 1.00 Uij C15 1.2344(2) 0.2260(2) 1.2803(2) 0.0520(10) 1.00 Uij C16 1.1740(2) 0.3065(2) 1.2136(2) 0.0470(10) 1.00 Uij C17 1.0468(2) 0.2925(2) 1.1534(2) 0.0400(10) 1.00 Uij C18 0.7257(2) 0.2213(2) 1.0782(2) 0.0360(10) 1.00 Uij C19 0.6548(3) 0.2499(2) 1.2508(2) 0.0530(10) 1.00 Uij C20 0.6117(3) 0.3202(2) 1.3362(2) 0.070(2) 1.00 Uij C21 0.6349(3) -0.0003(2) 0.8922(2) 0.0490(10) 1.00 Uij H1 1.0387(7) 0.4154(6) 1.0479(5) 0.05460 1.00 Uiso H10 0.90113 0.03017 1.01229 0.05153 1.00 Uiso H13 0.99759 0.04567 1.22929 0.05331 1.00 Uiso H14 1.20761 0.07419 1.33647 0.05581 1.00 Uiso H15 1.32310 0.23644 1.32102 0.05956 1.00 Uiso H16 1.21950 0.37415 1.20798 0.05483 1.00 Uiso H21 0.68877 -0.05955 0.87411 0.05684 1.00 Uiso H3A 0.75493 0.45892 1.20305 0.05001 1.00 Uiso H3B 0.8593(6) 0.3654(5) 1.2357(5) 0.05001 1.00 Uiso H5A 0.58195 0.40371 1.02551 0.05940 1.00 Uiso H5B 0.52135 0.41441 1.13131 0.05940 1.00 Uiso H6A 0.42093 0.24310 1.09851 0.06276 1.00 Uiso H6B 0.36913 0.32100 1.00261 0.06276 1.00 Uiso H7A 0.43779 0.14226 0.95370 0.05097 1.00 Uiso H7B 0.49669 0.23946 0.89660 0.05097 1.00 Uiso H19A 0.57578 0.18770 1.22419 0.06068 1.00 Uiso H19B 0.73598 0.21400 1.28399 0.06068 1.00 Uiso H20A 0.59749 0.27708 1.39640 0.07801 1.00 Uiso H20B 0.52919 0.35638 1.30670 0.07801 1.00 Uiso H20C 0.68069 0.37308 1.35900 0.07801 1.00 Uiso loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_12 _atom_site_aniso_U_13 _atom_site_aniso_U_23 O1 0.0500(10) 0.0500(10) 0.0720(10) 0.0018(8) 0.0105(9) 0.0233(9) O2 0.0650(10) 0.0530(10) 0.0640(10) -.0070(10) -.0080(10) -.0096(8) N1 0.0430(10) 0.0440(10) 0.0530(10) -.0010(10) 0.0126(9) 0.0120(9) N8 0.0380(10) 0.0360(10) 0.0363(9) -.0006(9) 0.0072(8) 0.0000(8) C2 0.041(2) 0.0350(10) 0.0480(10) -.0080(10) 0.0040(10) 0.0020(10) C3 0.0450(10) 0.0360(10) 0.0450(10) -.0020(10) 0.0100(10) -.0040(10) C4 0.0420(10) 0.0360(10) 0.0400(10) -.0030(10) 0.0100(10) -.0040(10) C5 0.050(2) 0.0440(10) 0.0600(10) 0.0060(10) 0.0090(10) -.0120(10) C6 0.0400(10) 0.059(2) 0.066(2) 0.0030(10) 0.0060(10) -.0100(10) C7 0.0340(10) 0.0480(10) 0.0480(10) 0.0000(10) 0.0020(10) 0.0010(10) C9 0.0430(10) 0.0340(10) 0.0400(10) -.0030(10) 0.0080(10) -.0040(10) C10 0.043(2) 0.0400(10) 0.0480(10) 0.0040(10) 0.0110(10) 0.0000(10) C11 0.0400(10) 0.0320(10) 0.0400(10) 0.0000(10) 0.0050(10) 0.0020(10) C12 0.0390(10) 0.0360(10) 0.0410(10) 0.0020(10) 0.0070(10) -.0010(10) C13 0.051(2) 0.0360(10) 0.0500(10) 0.0030(10) 0.0050(10) 0.0010(10) C14 0.050(2) 0.050(2) 0.0440(10) 0.0120(10) 0.0020(10) -.0010(10) C15 0.038(2) 0.062(2) 0.0550(10) 0.0050(10) 0.0020(10) -.0100(10) C16 0.0400(10) 0.0450(10) 0.0550(10) -.0070(10) 0.0100(10) -.0050(10) C17 0.0390(10) 0.0390(10) 0.0420(10) 0.0030(10) 0.0090(10) 0.0030(10) C18 0.0420(10) 0.0320(10) 0.0330(10) -.0020(10) 0.0060(10) 0.0010(10) C19 0.058(2) 0.0460(10) 0.0540(10) -.0120(10) 0.0180(10) -.0100(10) C20 0.076(2) 0.075(2) 0.060(2) -.015(2) 0.0240(10) -.0060(10) C21 0.061(2) 0.0410(10) 0.0440(10) -.0030(10) 0.0110(10) -.0030(10) loop_ _geom_torsion_atom_site_label_1 _geom_torsion_atom_site_label_2 _geom_torsion_atom_site_label_3 _geom_torsion_atom_site_label_4 _geom_torsion _geom_torsion_site_symmetry_1 _geom_torsion_site_symmetry_2 _geom_torsion_site_symmetry_3 _geom_torsion_site_symmetry_4 _geom_torsion_publ_flag C17 N1 C2 O1 179.2(4) . . . . ? C2 N1 C17 C12 61.5(3) . . . . ? C2 N1 C17 C16 -120.3(4) . . . . ? C7 N8 C9 C10 172.9(3) . . . . ? C7 N8 C9 C21 -8.2(3) . . . . ? C7 N8 C18 C11 -172.2(3) . . . . ? C18 N8 C9 C10 -0.1(2) . . . . ? C9 N8 C18 C11 0.8(2) . . . . ? C18 N8 C9 C21 178.8(3) . . . . ? N8 C9 C10 C11 -0.6(2) . . . . ? N8 C9 C21 O2 1.4(3) . . . . ? C10 C9 C21 O2 -179.9(5) . . . . ? C21 C9 C10 C11 -179.5(4) . . . . ? C9 C10 C11 C12 178.3(3) . . . . ? C9 C10 C11 C18 1.1(2) . . . . ? C10 C11 C12 C13 -52.5(3) . . . . ? C10 C11 C12 C17 123.5(4) . . . . ? C10 C11 C18 N8 -1.2(2) . . . . ? C12 C11 C18 N8 -178.3(4) . . . . ? C18 C11 C12 C13 124.1(4) . . . . ? C18 C11 C12 C17 -59.9(3) . . . . ? C11 C12 C13 C14 175.1(4) . . . . ? C11 C12 C17 N1 4.7(2) . . . . ? C11 C12 C17 C16 -173.4(4) . . . . ? C13 C12 C17 N1 -179.2(4) . . . . ? C17 C12 C13 C14 -1.1(3) . . . . ? C13 C12 C17 C16 2.7(3) . . . . ? C12 C13 C14 C15 -0.9(3) . . . . ? C13 C14 C15 C16 1.4(3) . . . . ? C14 C15 C16 C17 0.2(3) . . . . ? C15 C16 C17 N1 179.6(4) . . . . ? C15 C16 C17 C12 -2.3(3) . . . . ? H1 N1 C2 O1 16.0(6) . . . . ? H1 N1 C17 C12 -136.4(6) . . . . ? H1 N1 C17 C16 41.7(6) . . . . ? _geom_special_details ; All standard uncertainties (except dihedral angles between l.s. planes) are estimated using the full covariance matrix. The standard uncertainties in cell dimensions are are used in calculating the standard uncertainties of bond distances, angles and torsion angles. Angles between l.s. planes have standard uncertainties calculated from atomic positional standard uncertainties- the errors in cell dimensions are not used in this case. ; loop_ _geom_bond_atom_site_label_1 _geom_bond_atom_site_label_2 _geom_bond_distance _geom_bond_site_symmetry_1 _geom_bond_site_symmetry_2 _geom_bond_publ_flag O1 C2 1.241(3) . . ? O2 C21 1.213(3) . . ? N1 C2 1.349(3) . . ? N1 C17 1.425(3) . . ? N8 C7 1.464(3) . . ? N8 C9 1.387(3) . . ? N8 C18 1.364(3) . . ? C9 C10 1.370(3) . . ? C9 C21 1.430(3) . . ? C10 C11 1.399(3) . . ? C11 C12 1.477(3) . . ? C11 C18 1.397(3) . . ? C12 C13 1.401(3) . . ? C12 C17 1.399(3) . . ? C13 C14 1.375(4) . . ? C14 C15 1.377(4) . . ? C15 C16 1.376(4) . . ? C16 C17 1.385(4) . . ? N1 H1 0.885(2) . . ? 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_2 _geom_angle_site_symmetry_3 _geom_angle_publ_flag C2 N1 C17 126.0(2) . . . ? C7 N8 C9 125.2(2) . . . ? C7 N8 C18 125.6(2) . . . ? C9 N8 C18 108.8(2) . . . ? O1 C2 N1 120.4(2) . . . ? N8 C9 C10 107.3(2) . . . ? N8 C9 C21 126.8(3) . . . ? C10 C9 C21 125.9(3) . . . ? C9 C10 C11 109.3(2) . . . ? C10 C11 C12 124.9(2) . . . ? C10 C11 C18 106.0(2) . . . ? C12 C11 C18 129.0(2) . . . ? C11 C12 C13 119.3(2) . . . ? C11 C12 C17 123.3(2) . . . ? C13 C12 C17 117.3(2) . . . ? C12 C13 C14 122.4(3) . . . ? C13 C14 C15 119.3(3) . . . ? C14 C15 C16 119.8(3) . . . ? C15 C16 C17 121.3(3) . . . ? N1 C17 C12 120.8(2) . . . ? N1 C17 C16 119.3(2) . . . ? C12 C17 C16 119.9(3) . . . ? N8 C18 C11 108.7(2) . . . ? O2 C21 C9 129.0(3) . . . ? C2 N1 H1 112.3(2) . . . ? C17 N1 H1 119.5(2) . . . ? loop_ _geom_contact_atom_site_label_1 _geom_contact_atom_site_label_2 _geom_contact_distance _geom_contact_site_symmetry_1 _geom_contact_site_symmetry_2 _geom_contact_publ_flag O1 N1 2.913(2) 1_555 2_767 ? O1 H1 2.030(2) 1_555 2_767 ? O2 C2 3.430(3) 1_555 4_565 ? O2 C3 3.135(3) 1_555 4_565 ? O2 C7 3.472(3) 1_555 2_657 ? O2 C16 3.469(3) 1_555 4_565 ? O2 H3B 2.591(2) 1_555 4_565 ? O2 H19A 2.548(2) 1_555 2_657 ? N8 C15 3.446(3) 1_555 4_565 ? C2 H1 2.862(2) 1_555 2_767 ? C6 C16 3.798(3) 1_555 1_455 ? C6 C21 3.717(3) 1_555 2_657 ? C7 C13 3.849(3) 1_555 4_565 ? C7 C14 3.671(3) 1_555 4_565 ? C7 C15 3.709(3) 1_555 4_565 ? C7 C16 3.898(3) 1_555 4_565 ? C7 C20 3.939(4) 1_555 4_565 ? C7 C21 3.490(3) 1_555 2_657 ? C7 H3B 3.110(2) 1_555 4_565 ? C9 C15 3.451(3) 1_555 4_565 ? C9 C16 3.494(3) 1_555 4_565 ? C10 C15 3.849(3) 1_555 4_565 ? C10 C20 3.683(4) 1_555 3_647 ? C10 H10 3.115(2) 1_555 2_757 ? C10 H20C 2.985(2) 1_555 3_647 ? C12 H7B 3.125(2) 1_555 4_666 ? C13 C20 3.967(4) 1_555 3_647 ? C13 H5B 3.181(2) 1_555 3_647 ? C13 H7B 2.913(2) 1_555 4_666 ? C14 C21 3.629(3) 1_555 2_757 ? C14 H21 2.829(2) 1_555 2_757 ? C14 H7B 2.876(2) 1_555 4_666 ? C15 C18 3.847(3) 1_555 4_666 ? C15 C20 3.911(4) 1_555 1_655 ? C15 C21 3.901(3) 1_555 2_757 ? C15 C21 3.862(3) 1_555 4_666 ? C15 H21 3.024(2) 1_555 2_757 ? C15 H7B 3.038(2) 1_555 4_666 ? C16 C21 3.360(3) 1_555 4_666 ? C16 H6A 3.177(2) 1_555 1_655 ? C17 C21 3.951(3) 1_555 4_666 ? C20 H13 3.053(3) 1_555 3_657 ? C20 H15 3.051(3) 1_555 1_455 ? C21 H16 3.043(2) 1_555 4_565 ? C21 H6A 3.052(2) 1_555 2_657 ? C21 H7A 2.809(2) 1_555 2_657 ? H10 H10 2.1908 1_555 2_757 ? H13 H20B 2.3849 1_555 3_647 ? O1 N1 2.913(2) 1_555 2_767 ? O1 H1 2.030(2) 1_555 2_767 ? O2 C2 3.430(3) 1_555 4_565 ? O2 C3 3.135(3) 1_555 4_565 ? O2 C7 3.472(3) 1_555 2_657 ? O2 C16 3.469(3) 1_555 4_565 ? O2 H3B 2.591(2) 1_555 4_565 ? O2 H19A 2.548(2) 1_555 2_657 ? N8 C15 3.446(3) 1_555 4_565 ? C2 H1 2.862(2) 1_555 2_767 ? C6 C16 3.798(3) 1_555 1_455 ? C6 C21 3.717(3) 1_555 2_657 ? C7 C13 3.849(3) 1_555 4_565 ? C7 C14 3.671(3) 1_555 4_565 ? C7 C15 3.709(3) 1_555 4_565 ? C7 C16 3.898(3) 1_555 4_565 ? C7 C20 3.939(4) 1_555 4_565 ? C7 C21 3.490(3) 1_555 2_657 ? C7 H3B 3.110(2) 1_555 4_565 ? C9 C15 3.451(3) 1_555 4_565 ? C9 C16 3.494(3) 1_555 4_565 ? C10 C15 3.849(3) 1_555 4_565 ? C10 C20 3.683(4) 1_555 3_647 ? C10 H10 3.115(2) 1_555 2_757 ? C10 H20C 2.985(2) 1_555 3_647 ? C12 H7B 3.125(2) 1_555 4_666 ? C13 C20 3.967(4) 1_555 3_647 ? C13 H5B 3.181(2) 1_555 3_647 ? C13 H7B 2.913(2) 1_555 4_666 ? C14 C21 3.629(3) 1_555 2_757 ? C14 H21 2.829(2) 1_555 2_757 ? C14 H7B 2.876(2) 1_555 4_666 ? C15 C18 3.847(3) 1_555 4_666 ? C15 C20 3.911(4) 1_555 1_655 ? C15 C21 3.901(3) 1_555 2_757 ? C15 C21 3.862(3) 1_555 4_666 ? C15 H21 3.024(2) 1_555 2_757 ? C15 H7B 3.038(2) 1_555 4_666 ? C16 C21 3.360(3) 1_555 4_666 ? C16 H6A 3.177(2) 1_555 1_655 ? C17 C21 3.951(3) 1_555 4_666 ? C20 H13 3.053(3) 1_555 3_657 ? C20 H15 3.051(3) 1_555 1_455 ? C21 H16 3.043(2) 1_555 4_565 ? C21 H6A 3.052(2) 1_555 2_657 ? C21 H7A 2.809(2) 1_555 2_657 ? H10 H10 2.1908 1_555 2_757 ? H13 H20B 2.3849 1_555 3_647 ? #=================================================== _publ_section_references ; Mackay, S., Gilmore, C. J.,Edwards, C., Stewart, N. & Shankland, K. (1999). maXus Computer Program for the Solution and Refinement of Crystal Structures. Nonius, The Netherlands, MacScience, Japan & The University of Glasgow. Altomare, A., Cascarano, G., Giacovazzo, C., Guagliardi, A., Burla, M. C., Polidori, G. & Camalli, M. (1994). J. Appl. Cryst. 27, 435. Waasmaier, D. & Kirfel, A. (1995). Acta Cryst. A51, 416-431. ;