#------------------------------------------------------------------------------ #$Date: 2013-12-28 15:58:47 +0200 (Sat, 28 Dec 2013) $ #$Revision: 91933 $ #$URL: file:///home/coder/svn-repositories/cod/cif/2/01/31/2013185.cif $ #------------------------------------------------------------------------------ # # This file is available in the Crystallography Open Database (COD), # http://www.crystallography.net/. The original data for this entry # were provided by IUCr Journals, http://journals.iucr.org/. # # The file may be used within the scientific community so long as # proper attribution is given to the journal article from which the # data were obtained. # data_2013185 loop_ _publ_author_name 'Sivakumar, B.' 'Sethu Sankar, K.' 'Senthil Kumar, U. P.' 'Jeyaraman, R.' 'Velmurugan, D.' _publ_section_title ; 2-Nitroso-1,3-diphenyl-1,2,3,4-tetrahydrobenzo[b][1,6]naphthyridine ; _journal_issue 3 _journal_name_full 'Acta Crystallographica Section C' _journal_page_first o153 _journal_page_last o155 _journal_volume 59 _journal_year 2003 _chemical_formula_moiety 'C24 H19 N3 O' _chemical_formula_sum 'C24 H19 N3 O' _chemical_formula_weight 365.42 _chemical_name_systematic ; 2-Nitroso-1,3-diphenyl-1,2,3,4-tetrahydrobenzo[b][1,6]naphthyridine ; _space_group_IT_number 14 _symmetry_cell_setting monoclinic _symmetry_space_group_name_Hall '-P 2yab' _symmetry_space_group_name_H-M 'P 1 21/a 1' _atom_sites_solution_hydrogens geom _atom_sites_solution_primary direct _atom_sites_solution_secondary difmap _audit_creation_method SHELXL97 _cell_angle_alpha 90 _cell_angle_beta 105.74(3) _cell_angle_gamma 90 _cell_formula_units_Z 4 _cell_length_a 9.713(6) _cell_length_b 19.265(8) _cell_length_c 10.450(2) _cell_measurement_reflns_used 25 _cell_measurement_temperature 293(2) _cell_measurement_theta_max 68.02 _cell_measurement_theta_min 4.40 _cell_volume 1882.1(15) _computing_cell_refinement 'CAD-4 EXPRESS' _computing_data_collection 'CAD-4 EXPRESS (Enraf-Nonius, 1994)' _computing_data_reduction 'XCAD4 (Harms & Wocadlo, 1995)' _computing_molecular_graphics 'ZORTEP (Zsolnai, 1997) and PLATON (Spek, 2000)' _computing_publication_material 'SHELX97 and PARST (Nardelli, 1995)' _computing_structure_refinement 'SHELXL97 (Sheldrick, 1997)' _computing_structure_solution 'SHELXS97 (Sheldrick, 1997)' _diffrn_ambient_temperature 293(2) _diffrn_measurement_device_type 'Enraf-Nonius CAD-4' _diffrn_measurement_method 'non-profiled w/2\q' _diffrn_radiation_monochromator graphite _diffrn_radiation_source 'fine-focus sealed tube' _diffrn_radiation_type CuK\a _diffrn_radiation_wavelength 1.54180 _diffrn_reflns_av_R_equivalents 0.052 _diffrn_reflns_av_sigmaI/netI 0.021 _diffrn_reflns_limit_h_max 11 _diffrn_reflns_limit_h_min -11 _diffrn_reflns_limit_k_max 23 _diffrn_reflns_limit_k_min 0 _diffrn_reflns_limit_l_max 12 _diffrn_reflns_limit_l_min -12 _diffrn_reflns_number 3876 _diffrn_reflns_theta_full 68.02 _diffrn_reflns_theta_max 68.02 _diffrn_reflns_theta_min 4.40 _diffrn_standards_decay_% 0 _diffrn_standards_interval_count 100 _diffrn_standards_interval_time 120 _diffrn_standards_number 3 _exptl_absorpt_coefficient_mu 0.636 _exptl_absorpt_correction_type none _exptl_crystal_colour 'pale yellow' _exptl_crystal_density_diffrn 1.290 _exptl_crystal_density_meas 'not measured' _exptl_crystal_density_method 'not measured' _exptl_crystal_description plate _exptl_crystal_F_000 768 _exptl_crystal_size_max 0.2 _exptl_crystal_size_mid 0.2 _exptl_crystal_size_min 0.15 _refine_diff_density_max 0.23 _refine_diff_density_min -0.20 _refine_ls_extinction_method none _refine_ls_goodness_of_fit_ref 1.066 _refine_ls_hydrogen_treatment constr _refine_ls_matrix_type full _refine_ls_number_parameters 253 _refine_ls_number_reflns 3435 _refine_ls_number_restraints 0 _refine_ls_restrained_S_all 1.066 _refine_ls_R_factor_all 0.069 _refine_ls_R_factor_gt 0.057 _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^)+(0.1135P)^2^+0.1670P] where P=(Fo^2^+2Fc^2^)/3' _refine_ls_weighting_scheme calc _refine_ls_wR_factor_gt 0.160 _refine_ls_wR_factor_ref 0.172 _reflns_number_gt 2660 _reflns_number_total 3435 _reflns_threshold_expression I>2\s(I) _[local]_cod_data_source_file na1587.cif _[local]_cod_data_source_block I _[local]_cod_cif_authors_sg_H-M 'P 21/a' _cod_depositor_comments ; The following automatic conversions were performed: '_symmetry_cell_setting' value 'Monoclinic' changed to 'monoclinic' according to '/home/saulius/struct/CIF-dictionaries/cif_core.dic' dictionary named 'cif_core.dic' version 2.4.1 from 2010-06-29. Automatic conversion script Id: cif_fix_enum 1527 2010-12-29 10:47:43Z saulius The following automatic conversions were performed: '_symmetry_cell_setting' value 'Monoclinic' changed to 'monoclinic' according to /home/saulius/struct/CIF-dictionaries/cif_core.dic dictionary named 'cif_core.dic' version 2.4.1 from 2010-06-29. Automatic conversion script Id: cif_fix_values 1715 2011-07-08 13:25:40Z adriana ; _cod_original_cell_volume 1882.1(14) _cod_database_code 2013185 loop_ _symmetry_equiv_pos_as_xyz 'x, y, z' '-x+1/2, y+1/2, -z' '-x, -y, -z' 'x-1/2, -y-1/2, z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv _atom_site_adp_type _atom_site_calc_flag _atom_site_refinement_flags _atom_site_occupancy _atom_site_disorder_assembly _atom_site_disorder_group _atom_site_type_symbol O -0.2538(2) 0.74971(9) -0.15540(15) 0.0822(5) Uani d . 1 . . O N1 0.26428(18) 0.85872(8) 0.22203(15) 0.0560(4) Uani d . 1 . . N N2 -0.14707(17) 0.81452(8) 0.00869(15) 0.0519(4) Uani d . 1 . . N N3 -0.2456(2) 0.76712(9) -0.04006(17) 0.0672(5) Uani d . 1 . . N C1 0.0730(2) 0.88174(11) 0.02359(18) 0.0566(5) Uani d . 1 . . C H1A 0.1525 0.8831 -0.0160 0.068 Uiso calc R 1 . . H H1B 0.0397 0.9290 0.0268 0.068 Uiso calc R 1 . . H C2 -0.0481(2) 0.83912(9) -0.06702(18) 0.0510(4) Uani d . 1 . . C H2 -0.0053 0.7982 -0.0967 0.061 Uiso calc R 1 . . H C3 -0.1325(2) 0.83110(10) 0.15039(18) 0.0536(5) Uani d . 1 . . C H3 -0.1762 0.7925 0.1863 0.064 Uiso calc R 1 . . H C4 0.0682(2) 0.81396(10) 0.3577(2) 0.0571(5) Uani d . 1 . . C H4 0.0027 0.7977 0.4010 0.069 Uiso calc R 1 . . H C5 0.2679(3) 0.80539(12) 0.5640(2) 0.0682(6) Uani d . 1 . . C H5 0.2064 0.7903 0.6126 0.082 Uiso calc R 1 . . H C6 0.4089(3) 0.81350(11) 0.6254(2) 0.0716(6) Uani d . 1 . . C H6 0.4427 0.8043 0.7159 0.086 Uiso calc R 1 . . H C7 0.5048(3) 0.83554(11) 0.5549(2) 0.0681(6) Uani d . 1 . . C H7 0.6014 0.8407 0.5983 0.082 Uiso calc R 1 . . H C8 0.4556(2) 0.84951(11) 0.4216(2) 0.0636(5) Uani d . 1 . . C H8 0.5194 0.8643 0.3751 0.076 Uiso calc R 1 . . H C9 0.3103(2) 0.84176(9) 0.35445(19) 0.0538(5) Uani d . 1 . . C C10 0.2133(2) 0.81961(9) 0.42672(19) 0.0561(5) Uani d . 1 . . C C11 0.1265(2) 0.85525(10) 0.16292(18) 0.0518(4) Uani d . 1 . . C C12 0.0236(2) 0.83237(9) 0.22719(18) 0.0515(4) Uani d . 1 . . C C13 -0.2166(2) 0.89604(10) 0.16495(17) 0.0532(5) Uani d . 1 . . C C14 -0.3646(2) 0.89194(13) 0.1294(2) 0.0685(6) Uani d . 1 . . C H14 -0.4091 0.8505 0.0961 0.082 Uiso calc R 1 . . H C15 -0.4473(3) 0.94873(15) 0.1426(3) 0.0781(7) Uani d . 1 . . C H15 -0.5466 0.9454 0.1186 0.094 Uiso calc R 1 . . H C16 -0.3817(3) 1.00969(14) 0.1911(3) 0.0796(7) Uani d . 1 . . C H16 -0.4367 1.0480 0.2001 0.095 Uiso calc R 1 . . H C17 -0.2354(3) 1.01483(13) 0.2266(2) 0.0729(6) Uani d . 1 . . C H17 -0.1918 1.0567 0.2588 0.087 Uiso calc R 1 . . H C18 -0.1518(2) 0.95774(11) 0.2149(2) 0.0613(5) Uani d . 1 . . C H18 -0.0526 0.9612 0.2406 0.074 Uiso calc R 1 . . H C19 -0.12092(19) 0.88110(9) -0.18879(17) 0.0487(4) Uani d . 1 . . C C20 -0.0778(2) 0.87241(11) -0.30400(19) 0.0610(5) Uani d . 1 . . C H20 -0.0128 0.8377 -0.3084 0.073 Uiso calc R 1 . . H C21 -0.1313(3) 0.91526(13) -0.4122(2) 0.0713(6) Uani d . 1 . . C H21 -0.1010 0.9093 -0.4887 0.086 Uiso calc R 1 . . H C22 -0.2287(3) 0.96660(12) -0.4083(2) 0.0689(6) Uani d . 1 . . C H22 -0.2635 0.9955 -0.4813 0.083 Uiso calc R 1 . . H C23 -0.2742(2) 0.97476(11) -0.2953(2) 0.0634(5) Uani d . 1 . . C H23 -0.3417 1.0085 -0.2925 0.076 Uiso calc R 1 . . H C24 -0.2195(2) 0.93276(10) -0.18588(19) 0.0558(5) Uani d . 1 . . C H24 -0.2492 0.9393 -0.1093 0.067 Uiso calc R 1 . . H 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 O 0.0965(13) 0.0837(11) 0.0689(10) -0.0292(9) 0.0266(9) -0.0193(8) N1 0.0563(10) 0.0551(9) 0.0562(9) -0.0051(7) 0.0148(7) 0.0006(7) N2 0.0516(9) 0.0517(8) 0.0536(8) -0.0102(7) 0.0163(7) -0.0031(6) N3 0.0756(12) 0.0641(10) 0.0609(10) -0.0189(9) 0.0168(9) -0.0077(8) C1 0.0520(11) 0.0630(11) 0.0554(10) -0.0091(9) 0.0156(9) 0.0051(8) C2 0.0517(11) 0.0504(9) 0.0540(10) -0.0011(8) 0.0196(8) -0.0020(7) C3 0.0583(12) 0.0568(10) 0.0494(10) -0.0075(8) 0.0207(8) 0.0039(8) C4 0.0651(12) 0.0527(10) 0.0556(10) -0.0024(9) 0.0196(9) 0.0070(8) C5 0.0779(15) 0.0669(13) 0.0562(11) 0.0001(11) 0.0121(10) 0.0109(9) C6 0.0878(17) 0.0592(12) 0.0579(12) -0.0039(11) 0.0029(11) 0.0046(9) C7 0.0636(13) 0.0549(11) 0.0753(13) 0.0004(9) 0.0005(11) 0.0001(9) C8 0.0603(13) 0.0588(11) 0.0673(12) -0.0019(9) 0.0097(10) 0.0008(9) C9 0.0573(11) 0.0432(9) 0.0585(10) -0.0005(8) 0.0117(9) -0.0008(7) C10 0.0635(12) 0.0467(9) 0.0563(11) -0.0020(8) 0.0134(9) 0.0048(8) C11 0.0541(11) 0.0490(9) 0.0534(10) -0.0029(8) 0.0167(8) 0.0003(7) C12 0.0549(11) 0.0479(9) 0.0521(10) -0.0045(8) 0.0153(8) 0.0012(7) C13 0.0539(11) 0.0636(11) 0.0475(9) -0.0037(8) 0.0231(8) 0.0041(8) C14 0.0547(12) 0.0814(14) 0.0752(13) -0.0093(10) 0.0274(10) -0.0064(11) C15 0.0491(12) 0.1019(18) 0.0882(16) 0.0055(12) 0.0269(11) -0.0037(14) C16 0.0764(16) 0.0807(16) 0.0917(16) 0.0113(13) 0.0399(13) -0.0009(13) C17 0.0743(15) 0.0663(13) 0.0873(15) 0.0003(11) 0.0376(13) -0.0034(11) C18 0.0534(11) 0.0657(12) 0.0686(12) -0.0046(9) 0.0228(9) -0.0019(9) C19 0.0461(10) 0.0514(9) 0.0494(9) -0.0049(7) 0.0144(8) -0.0027(7) C20 0.0687(13) 0.0633(11) 0.0575(11) -0.0006(10) 0.0281(10) -0.0051(9) C21 0.0887(17) 0.0784(14) 0.0544(11) -0.0057(12) 0.0322(11) 0.0018(10) C22 0.0809(15) 0.0644(12) 0.0605(12) -0.0058(11) 0.0176(11) 0.0099(10) C23 0.0666(13) 0.0534(11) 0.0700(12) 0.0066(9) 0.0180(10) 0.0060(9) C24 0.0574(11) 0.0573(11) 0.0556(10) 0.0024(8) 0.0204(9) -0.0024(8) loop_ _geom_bond_atom_site_label_1 _geom_bond_atom_site_label_2 _geom_bond_site_symmetry_2 _geom_bond_distance _geom_bond_publ_flag O N3 . 1.233(2) y N1 C11 . 1.315(3) y N1 C9 . 1.373(2) y N2 N3 . 1.321(2) y N2 C2 . 1.479(2) y N2 C3 . 1.484(2) y C1 C11 . 1.497(3) y C1 C2 . 1.533(3) ? C1 H1A . 0.9700 ? C1 H1B . 0.9700 ? C2 C19 . 1.512(3) y C2 H2 . 0.9800 ? C3 C12 . 1.511(3) ? C3 C13 . 1.524(3) y C3 H3 . 0.9800 ? C4 C12 . 1.361(3) ? C4 C10 . 1.402(3) ? C4 H4 . 0.9300 ? C5 C6 . 1.355(4) ? C5 C10 . 1.414(3) ? C5 H5 . 0.9300 ? C6 C7 . 1.401(4) ? C6 H6 . 0.9300 ? C7 C8 . 1.371(3) ? C7 H7 . 0.9300 ? C8 C9 . 1.404(3) ? C8 H8 . 0.9300 ? C9 C10 . 1.423(3) ? C11 C12 . 1.417(3) ? C13 C18 . 1.380(3) ? C13 C14 . 1.386(3) ? C14 C15 . 1.386(3) ? C14 H14 . 0.9300 ? C15 C16 . 1.366(4) ? C15 H15 . 0.9300 ? C16 C17 . 1.372(4) ? C16 H16 . 0.9300 ? C17 C18 . 1.392(3) ? C17 H17 . 0.9300 ? C18 H18 . 0.9300 ? C19 C24 . 1.387(3) ? C19 C20 . 1.388(2) ? C20 C21 . 1.383(3) ? C20 H20 . 0.9300 ? C21 C22 . 1.377(3) ? C21 H21 . 0.9300 ? C22 C23 . 1.377(3) ? C22 H22 . 0.9300 ? C23 C24 . 1.384(3) ? C23 H23 . 0.9300 ? C24 H24 . 0.9300 ? 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' N N 0.0311 0.0180 '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' loop_ _geom_angle_atom_site_label_1 _geom_angle_atom_site_label_2 _geom_angle_atom_site_label_3 _geom_angle _geom_angle_publ_flag C11 N1 C9 118.22(17) ? N3 N2 C2 121.6(2) y N3 N2 C3 113.4(2) y C2 N2 C3 124.43(15) ? O N3 N2 114.4(2) y C11 C1 C2 115.09(16) ? C11 C1 H1A 108.5 ? C2 C1 H1A 108.5 ? C11 C1 H1B 108.5 ? C2 C1 H1B 108.5 ? H1A C1 H1B 107.5 ? N2 C2 C19 113.48(16) ? N2 C2 C1 110.02(15) ? C19 C2 C1 109.79(15) ? N2 C2 H2 107.8 ? C19 C2 H2 107.8 ? C1 C2 H2 107.8 ? N2 C3 C12 110.1(2) y N2 C3 C13 111.6(2) y C12 C3 C13 114.93(16) ? N2 C3 H3 106.6 ? C12 C3 H3 106.6 ? C13 C3 H3 106.6 ? C12 C4 C10 119.84(19) ? C12 C4 H4 120.1 ? C10 C4 H4 120.1 ? C6 C5 C10 120.8(2) ? C6 C5 H5 119.6 ? C10 C5 H5 119.6 ? C5 C6 C7 121.1(2) ? C5 C6 H6 119.5 ? C7 C6 H6 119.5 ? C8 C7 C6 119.7(2) ? C8 C7 H7 120.1 ? C6 C7 H7 120.1 ? C7 C8 C9 120.9(2) ? C7 C8 H8 119.6 ? C9 C8 H8 119.6 ? N1 C9 C8 119.12(19) ? N1 C9 C10 121.65(18) ? C8 C9 C10 119.16(18) ? C4 C10 C5 123.7(2) ? C4 C10 C9 117.89(18) ? C5 C10 C9 118.4(2) ? N1 C11 C12 123.51(17) ? N1 C11 C1 118.72(17) ? C12 C11 C1 117.60(18) ? C4 C12 C11 118.81(19) ? C4 C12 C3 121.92(18) ? C11 C12 C3 119.25(17) ? C18 C13 C14 118.97(19) ? C18 C13 C3 122.89(18) ? C14 C13 C3 118.12(18) ? C13 C14 C15 121.0(2) ? C13 C14 H14 119.5 ? C15 C14 H14 119.5 ? C16 C15 C14 119.4(2) ? C16 C15 H15 120.3 ? C14 C15 H15 120.3 ? C15 C16 C17 120.5(2) ? C15 C16 H16 119.8 ? C17 C16 H16 119.8 ? C16 C17 C18 120.3(2) ? C16 C17 H17 119.8 ? C18 C17 H17 119.8 ? C13 C18 C17 119.8(2) ? C13 C18 H18 120.1 ? C17 C18 H18 120.1 ? C24 C19 C20 118.55(18) ? C24 C19 C2 122.24(16) ? C20 C19 C2 118.91(17) ? C21 C20 C19 120.2(2) ? C21 C20 H20 119.9 ? C19 C20 H20 119.9 ? C22 C21 C20 120.86(19) ? C22 C21 H21 119.6 ? C20 C21 H21 119.6 ? C23 C22 C21 119.3(2) ? C23 C22 H22 120.3 ? C21 C22 H22 120.3 ? C22 C23 C24 120.1(2) ? C22 C23 H23 120.0 ? C24 C23 H23 120.0 ? C23 C24 C19 120.94(18) ? C23 C24 H24 119.5 ? C19 C24 H24 119.5 ? 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_publ_flag C2 N2 N3 O -5.0(3) y C3 N2 N3 O -176.1(2) y N3 N2 C2 C19 68.4(2) ? C3 N2 C2 C19 -121.55(19) ? N3 N2 C2 C1 -168.15(18) ? C3 N2 C2 C1 1.9(2) ? C11 C1 C2 N2 38.0(2) ? C11 C1 C2 C19 163.6(2) y N3 N2 C3 C12 133.87(17) ? C2 N2 C3 C12 -36.9(2) ? N3 N2 C3 C13 -97.3(2) ? C2 N2 C3 C13 92.0(2) ? C10 C5 C6 C7 -0.6(4) ? C5 C6 C7 C8 0.3(3) ? C6 C7 C8 C9 -0.2(3) ? C11 N1 C9 C8 -175.84(17) ? C11 N1 C9 C10 1.2(3) ? C7 C8 C9 N1 177.61(18) ? C7 C8 C9 C10 0.5(3) ? C12 C4 C10 C5 176.35(19) ? C12 C4 C10 C9 -2.8(3) ? C6 C5 C10 C4 -178.4(2) ? C6 C5 C10 C9 0.8(3) ? N1 C9 C10 C4 1.4(3) ? C8 C9 C10 C4 178.49(18) ? N1 C9 C10 C5 -177.79(18) ? C8 C9 C10 C5 -0.7(3) ? C9 N1 C11 C12 -2.5(3) ? C9 N1 C11 C1 172.66(16) ? C2 C1 C11 N1 142.07(18) ? C2 C1 C11 C12 -42.5(2) ? C10 C4 C12 C11 1.7(3) ? C10 C4 C12 C3 -176.49(17) ? N1 C11 C12 C4 1.1(3) y C1 C11 C12 C4 -174.12(17) ? N1 C11 C12 C3 179.35(17) ? C1 C11 C12 C3 4.1(3) y N2 C3 C12 C4 -148.61(17) ? C13 C3 C12 C4 84.4(2) ? N2 C3 C12 C11 33.2(2) ? C13 C3 C12 C11 -93.8(2) y N2 C3 C13 C18 -110.5(2) ? C12 C3 C13 C18 15.8(2) ? N2 C3 C13 C14 71.2(2) ? C12 C3 C13 C14 -162.57(17) ? C18 C13 C14 C15 0.4(3) ? C3 C13 C14 C15 178.8(2) ? C13 C14 C15 C16 0.2(4) ? C14 C15 C16 C17 -0.1(4) ? C15 C16 C17 C18 -0.6(4) ? C14 C13 C18 C17 -1.0(3) ? C3 C13 C18 C17 -179.34(18) ? C16 C17 C18 C13 1.2(3) ? N2 C2 C19 C24 45.2(2) ? C1 C2 C19 C24 -78.4(2) y N2 C2 C19 C20 -141.18(17) ? C1 C2 C19 C20 95.2(2) ? C24 C19 C20 C21 0.9(3) ? C2 C19 C20 C21 -173.01(19) ? C19 C20 C21 C22 -0.7(3) ? C20 C21 C22 C23 -0.6(4) ? C21 C22 C23 C24 1.5(3) ? C22 C23 C24 C19 -1.3(3) ? C20 C19 C24 C23 0.1(3) ? C2 C19 C24 C23 173.79(18) ? _cod_database_fobs_code 2013185 _journal_paper_doi 10.1107/S0108270102022758