#------------------------------------------------------------------------------ #$Date: 2014-07-11 17:35:18 +0300 (Fri, 11 Jul 2014) $ #$Revision: 120071 $ #$URL: file:///home/coder/svn-repositories/cod/cif/1/50/47/1504708.cif $ #------------------------------------------------------------------------------ # # This file is available in the Crystallography Open Database (COD), # http://www.crystallography.net/ # # All data on this site have been placed in the public domain by the # contributors. # data_1504708 loop_ _publ_author_name 'Chung, Cheol K.' 'Grubbs, Robert H.' _publ_section_title ; Olefin metathesis catalyst: stabilization effect of backbone substitutions of N-heterocyclic carbene. ; _journal_issue 13 _journal_name_full 'Organic letters' _journal_page_first 2693 _journal_page_last 2696 _journal_volume 10 _journal_year 2008 _chemical_formula_moiety 'C29 H34 Cl2 N2 O Ru, C6 H6' _chemical_formula_sum 'C35 H40 Cl2 N2 O Ru' _chemical_formula_weight 676.66 _chemical_name_systematic ; ? ; _space_group_IT_number 2 _symmetry_cell_setting triclinic _symmetry_space_group_name_Hall '-P 1' _symmetry_space_group_name_H-M 'P -1' _audit_creation_method SHELXL-97 _cell_angle_alpha 78.5830(10) _cell_angle_beta 81.9420(10) _cell_angle_gamma 88.4040(10) _cell_formula_units_Z 2 _cell_length_a 10.3243(4) _cell_length_b 12.2628(5) _cell_length_c 12.8923(5) _cell_measurement_reflns_used 12191 _cell_measurement_temperature 100(2) _cell_measurement_theta_max 35.12 _cell_measurement_theta_min 2.39 _cell_volume 1584.13(11) _computing_cell_refinement 'Bruker SAINT v6.45A' _computing_data_collection 'Bruker SMART v5.630' _computing_data_reduction 'Bruker SAINT v6.45A' _computing_molecular_graphics 'Bruker XP v5.1' _computing_publication_material 'Bruker XCIF v6.12' _computing_structure_refinement 'Bruker XL v6.12' _computing_structure_solution 'Bruker XS v6.12' _diffrn_ambient_temperature 100(2) _diffrn_measured_fraction_theta_full 0.938 _diffrn_measured_fraction_theta_max 0.885 _diffrn_measurement_device_type 'Bruker SMART 1000' _diffrn_measurement_method '\w scans at 7 \f settings' _diffrn_radiation_monochromator graphite _diffrn_radiation_source 'fine-focus sealed tube' _diffrn_radiation_type MoK\a _diffrn_radiation_wavelength 0.71073 _diffrn_reflns_av_R_equivalents 0.0950 _diffrn_reflns_av_sigmaI/netI 0.1095 _diffrn_reflns_limit_h_max 16 _diffrn_reflns_limit_h_min -16 _diffrn_reflns_limit_k_max 20 _diffrn_reflns_limit_k_min -19 _diffrn_reflns_limit_l_max 20 _diffrn_reflns_limit_l_min -20 _diffrn_reflns_number 40231 _diffrn_reflns_theta_full 25.7 _diffrn_reflns_theta_max 36.06 _diffrn_reflns_theta_min 1.63 _exptl_absorpt_coefficient_mu 0.694 _exptl_absorpt_correction_T_max 0.9276 _exptl_absorpt_correction_T_min 0.9031 _exptl_absorpt_correction_type none _exptl_crystal_colour Brown/green _exptl_crystal_density_diffrn 1.419 _exptl_crystal_density_method 'not measured' _exptl_crystal_description Fragment _exptl_crystal_F_000 700 _exptl_crystal_size_max 0.15 _exptl_crystal_size_mid 0.12 _exptl_crystal_size_min 0.11 _refine_diff_density_max 1.507 _refine_diff_density_min -1.410 _refine_diff_density_rms 0.132 _refine_ls_extinction_method none _refine_ls_goodness_of_fit_ref 1.015 _refine_ls_number_parameters 376 _refine_ls_number_reflns 13346 _refine_ls_number_restraints 0 _refine_ls_restrained_S_all 1.015 _refine_ls_R_factor_all 0.0759 _refine_ls_R_factor_gt 0.0445 _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^) _refine_ls_weighting_scheme sigma _refine_ls_wR_factor_gt 0.0769 _refine_ls_wR_factor_ref 0.0829 _reflns_number_gt 8957 _reflns_number_total 13346 _reflns_threshold_expression >2sigma(I) _[local]_cod_data_source_file ol800824h-file003.cif _[local]_cod_data_source_block 13 _[local]_cod_cif_authors_sg_H-M P-1 _cod_depositor_comments ; The following automatic conversions were performed: '_symmetry_cell_setting' value 'Triclinic' changed to 'triclinic' according to /home/saulius/struct/CIF-dictionaries/cif_core.dic dictionary named 'cif_core.dic' version 2.4.1 from 2010-06-29. '_refine_ls_weighting_scheme' value 'Sigma' changed to 'sigma' 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_database_code 1504708 loop_ _symmetry_equiv_pos_as_xyz 'x, y, z' '-x, -y, -z' 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 Ru1 Ru 0.532455(16) 0.722205(14) 0.740207(13) 0.00934(4) Uani 1 1 d . Cl1 Cl 0.66593(5) 0.87860(4) 0.66581(4) 0.01456(10) Uani 1 1 d . Cl2 Cl 0.33941(5) 0.62153(4) 0.80474(4) 0.01288(10) Uani 1 1 d . O1 O 0.50310(14) 0.70716(12) 0.56948(11) 0.0133(3) Uani 1 1 d . N1 N 0.47823(15) 0.77557(13) 0.95363(12) 0.0098(3) Uani 1 1 d . N2 N 0.67317(15) 0.70253(13) 0.93454(13) 0.0101(3) Uani 1 1 d . C1 C 0.56688(18) 0.73037(16) 0.88411(16) 0.0100(4) Uani 1 1 d . C2 C 0.52036(19) 0.75841(16) 1.06316(15) 0.0106(4) Uani 1 1 d . C3 C 0.66986(19) 0.75684(16) 1.02941(15) 0.0117(4) Uani 1 1 d . C4 C 0.4753(2) 0.85193(17) 1.12193(17) 0.0155(4) Uani 1 1 d . H4A H 0.4948 0.9239 1.0739 0.023 Uiso 1 1 calc R H4B H 0.5212 0.8464 1.1843 0.023 Uiso 1 1 calc R H4C H 0.3808 0.8457 1.1453 0.023 Uiso 1 1 calc R C5 C 0.4690(2) 0.64545(17) 1.12831(16) 0.0150(4) Uani 1 1 d . H5A H 0.3731 0.6455 1.1373 0.023 Uiso 1 1 calc R H5B H 0.4988 0.6325 1.1986 0.023 Uiso 1 1 calc R H5C H 0.5022 0.5862 1.0906 0.023 Uiso 1 1 calc R C6 C 0.7291(2) 0.87303(17) 0.98852(17) 0.0146(4) Uani 1 1 d . H6A H 0.8196 0.8665 0.9554 0.022 Uiso 1 1 calc R H6B H 0.7275 0.9116 1.0484 0.022 Uiso 1 1 calc R H6C H 0.6779 0.9154 0.9356 0.022 Uiso 1 1 calc R C7 C 0.7462(2) 0.69205(18) 1.11456(16) 0.0163(4) Uani 1 1 d . H7A H 0.7153 0.6149 1.1342 0.024 Uiso 1 1 calc R H7B H 0.7330 0.7263 1.1778 0.024 Uiso 1 1 calc R H7C H 0.8395 0.6933 1.0865 0.024 Uiso 1 1 calc R C8 C 0.35934(19) 0.82659(16) 0.92633(15) 0.0108(4) Uani 1 1 d . C9 C 0.3597(2) 0.90067(17) 0.82890(16) 0.0133(4) Uani 1 1 d . H9 H 0.4396 0.9179 0.7826 0.016 Uiso 1 1 calc R C10 C 0.2441(2) 0.94917(18) 0.79934(17) 0.0177(4) Uani 1 1 d . H10 H 0.2451 0.9976 0.7319 0.021 Uiso 1 1 calc R C11 C 0.1269(2) 0.92770(18) 0.86716(18) 0.0190(5) Uani 1 1 d . H11 H 0.0478 0.9613 0.8469 0.023 Uiso 1 1 calc R C12 C 0.1273(2) 0.8562(2) 0.96516(19) 0.0220(5) Uani 1 1 d . H12 H 0.0480 0.8421 1.0129 0.026 Uiso 1 1 calc R C13 C 0.2418(2) 0.80528(18) 0.99434(17) 0.0169(4) Uani 1 1 d . H13 H 0.2401 0.7555 1.0611 0.020 Uiso 1 1 calc R C14 C 0.78967(18) 0.64963(17) 0.89310(16) 0.0117(4) Uani 1 1 d . C15 C 0.8800(2) 0.70926(18) 0.81284(17) 0.0163(4) Uani 1 1 d . H15 H 0.8668 0.7860 0.7858 0.020 Uiso 1 1 calc R C16 C 0.9900(2) 0.6542(2) 0.77308(19) 0.0231(5) Uani 1 1 d . H16 H 1.0517 0.6936 0.7176 0.028 Uiso 1 1 calc R C17 C 1.0107(2) 0.5432(2) 0.81308(19) 0.0223(5) Uani 1 1 d . H17 H 1.0856 0.5065 0.7847 0.027 Uiso 1 1 calc R C18 C 0.9219(2) 0.48526(18) 0.89487(18) 0.0175(4) Uani 1 1 d . H18 H 0.9367 0.4091 0.9232 0.021 Uiso 1 1 calc R C19 C 0.81111(19) 0.53870(17) 0.93542(16) 0.0128(4) Uani 1 1 d . H19 H 0.7505 0.4994 0.9918 0.015 Uiso 1 1 calc R C20 C 0.64305(19) 0.60834(16) 0.71728(16) 0.0117(4) Uani 1 1 d . H20 H 0.6881 0.5702 0.7732 0.014 Uiso 1 1 calc R C21 C 0.6625(2) 0.57569(16) 0.61379(16) 0.0126(4) Uani 1 1 d . C22 C 0.7525(2) 0.49371(18) 0.58943(18) 0.0176(4) Uani 1 1 d . H22 H 0.8031 0.4566 0.6420 0.021 Uiso 1 1 calc R C23 C 0.7681(2) 0.46653(19) 0.48885(19) 0.0226(5) Uani 1 1 d . H23 H 0.8301 0.4118 0.4720 0.027 Uiso 1 1 calc R C24 C 0.6926(2) 0.51970(19) 0.41324(18) 0.0218(5) Uani 1 1 d . H24 H 0.7023 0.4996 0.3451 0.026 Uiso 1 1 calc R C25 C 0.6030(2) 0.60186(18) 0.43455(16) 0.0166(4) Uani 1 1 d . H25 H 0.5526 0.6384 0.3816 0.020 Uiso 1 1 calc R C26 C 0.5887(2) 0.62939(16) 0.53531(16) 0.0128(4) Uani 1 1 d . C27 C 0.4331(2) 0.78051(18) 0.49043(16) 0.0168(4) Uani 1 1 d . H27 H 0.3945 0.7348 0.4462 0.020 Uiso 1 1 calc R C28 C 0.5274(2) 0.86483(19) 0.41845(18) 0.0227(5) Uani 1 1 d . H28A H 0.5684 0.9072 0.4621 0.034 Uiso 1 1 calc R H28B H 0.4796 0.9157 0.3685 0.034 Uiso 1 1 calc R H28C H 0.5951 0.8260 0.3783 0.034 Uiso 1 1 calc R C29 C 0.3246(2) 0.8338(2) 0.55441(18) 0.0229(5) Uani 1 1 d . H29A H 0.2728 0.7758 0.6053 0.034 Uiso 1 1 calc R H29B H 0.2683 0.8769 0.5061 0.034 Uiso 1 1 calc R H29C H 0.3624 0.8832 0.5934 0.034 Uiso 1 1 calc R C41 C 0.0376(3) 0.9421(2) 0.3627(2) 0.0303(6) Uani 1 1 d . H41 H 0.0542 1.0175 0.3642 0.036 Uiso 1 1 calc R C42 C 0.1178(3) 0.8881(2) 0.2962(2) 0.0375(7) Uani 1 1 d . H42 H 0.1907 0.9261 0.2520 0.045 Uiso 1 1 calc R C43 C 0.0945(3) 0.7798(3) 0.2922(2) 0.0464(8) Uani 1 1 d . H43 H 0.1514 0.7430 0.2457 0.056 Uiso 1 1 calc R C44 C -0.0112(3) 0.7242(2) 0.3557(3) 0.0443(8) Uani 1 1 d . H44 H -0.0286 0.6495 0.3518 0.053 Uiso 1 1 calc R C45 C -0.0924(3) 0.7775(2) 0.4256(2) 0.0387(7) Uani 1 1 d . H45 H -0.1640 0.7392 0.4712 0.046 Uiso 1 1 calc R C46 C -0.0673(3) 0.8872(2) 0.4277(2) 0.0316(6) Uani 1 1 d . H46 H -0.1228 0.9249 0.4743 0.038 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 Ru1 0.01079(7) 0.00962(7) 0.00743(7) -0.00124(6) -0.00103(5) -0.00103(5) Cl1 0.0156(2) 0.0125(2) 0.0143(2) -0.00027(19) 0.00010(18) -0.00374(19) Cl2 0.0133(2) 0.0136(2) 0.0117(2) -0.00259(18) -0.00069(17) -0.00380(18) O1 0.0180(7) 0.0134(7) 0.0083(6) -0.0013(6) -0.0025(6) 0.0000(6) N1 0.0106(7) 0.0131(8) 0.0065(7) -0.0034(6) -0.0022(6) 0.0013(6) N2 0.0096(7) 0.0120(8) 0.0099(7) -0.0045(6) -0.0028(6) 0.0009(6) C1 0.0095(8) 0.0073(8) 0.0123(9) -0.0001(7) -0.0008(7) -0.0020(7) C2 0.0134(9) 0.0117(9) 0.0077(8) -0.0036(7) -0.0027(7) 0.0013(7) C3 0.0120(9) 0.0129(9) 0.0108(9) -0.0029(8) -0.0031(7) 0.0014(8) C4 0.0162(10) 0.0174(10) 0.0146(10) -0.0076(8) -0.0020(8) 0.0028(8) C5 0.0163(10) 0.0139(10) 0.0134(10) 0.0011(8) -0.0019(8) -0.0010(8) C6 0.0147(10) 0.0138(10) 0.0161(10) -0.0043(8) -0.0024(8) -0.0019(8) C7 0.0179(10) 0.0186(10) 0.0135(10) -0.0032(8) -0.0072(8) 0.0040(8) C8 0.0108(9) 0.0108(9) 0.0118(9) -0.0043(8) -0.0027(7) 0.0010(7) C9 0.0144(9) 0.0141(10) 0.0122(9) -0.0042(8) -0.0026(8) 0.0033(8) C10 0.0223(11) 0.0168(10) 0.0153(10) -0.0039(9) -0.0069(9) 0.0034(9) C11 0.0122(10) 0.0200(11) 0.0267(12) -0.0053(10) -0.0090(9) 0.0040(8) C12 0.0112(10) 0.0281(12) 0.0251(12) -0.0028(10) -0.0007(9) -0.0004(9) C13 0.0137(10) 0.0201(11) 0.0151(10) -0.0004(9) -0.0007(8) 0.0005(8) C14 0.0086(9) 0.0151(10) 0.0119(9) -0.0042(8) -0.0017(7) 0.0011(7) C15 0.0142(10) 0.0153(10) 0.0188(10) -0.0033(9) -0.0003(8) -0.0008(8) C16 0.0135(10) 0.0281(13) 0.0258(12) -0.0043(10) 0.0033(9) -0.0022(9) C17 0.0108(10) 0.0310(13) 0.0264(12) -0.0103(11) -0.0015(9) 0.0063(9) C18 0.0151(10) 0.0179(10) 0.0207(11) -0.0058(9) -0.0047(9) 0.0045(8) C19 0.0129(9) 0.0149(10) 0.0114(9) -0.0039(8) -0.0033(7) 0.0019(8) C20 0.0150(9) 0.0101(9) 0.0099(9) -0.0017(7) -0.0012(7) -0.0024(8) C21 0.0148(9) 0.0102(9) 0.0118(9) -0.0024(8) 0.0027(8) -0.0043(8) C22 0.0164(10) 0.0167(10) 0.0198(11) -0.0068(9) 0.0018(8) 0.0005(8) C23 0.0244(12) 0.0209(11) 0.0235(12) -0.0126(10) 0.0050(9) -0.0008(9) C24 0.0270(12) 0.0243(12) 0.0148(10) -0.0119(9) 0.0076(9) -0.0092(10) C25 0.0235(11) 0.0173(10) 0.0088(9) -0.0035(8) 0.0019(8) -0.0074(9) C26 0.0154(10) 0.0109(9) 0.0117(9) -0.0031(8) 0.0018(8) -0.0051(8) C27 0.0198(11) 0.0193(11) 0.0099(9) 0.0019(8) -0.0044(8) -0.0009(9) C28 0.0325(13) 0.0192(11) 0.0155(10) 0.0002(9) -0.0042(10) -0.0023(10) C29 0.0253(12) 0.0263(12) 0.0166(11) -0.0021(10) -0.0057(9) 0.0061(10) C41 0.0304(14) 0.0287(13) 0.0322(14) -0.0040(11) -0.0077(11) -0.0037(11) C42 0.0288(14) 0.0350(15) 0.0363(15) 0.0111(12) 0.0124(12) 0.0026(12) C43 0.055(2) 0.0402(17) 0.0351(16) -0.0058(14) 0.0178(14) 0.0150(15) C44 0.0491(19) 0.0251(14) 0.059(2) -0.0108(14) -0.0040(16) -0.0018(13) C45 0.0195(13) 0.0361(16) 0.0510(18) 0.0065(14) 0.0078(12) -0.0065(12) C46 0.0290(14) 0.0392(16) 0.0251(13) -0.0077(12) 0.0023(11) 0.0039(12) 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 '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 0.0061 0.0033 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' O O 0.0106 0.0060 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' Cl Cl 0.1484 0.1585 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' Ru Ru -1.2594 0.8363 '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 C20 Ru1 C1 98.53(8) yes C20 Ru1 O1 78.37(7) yes C1 Ru1 O1 176.72(7) yes C20 Ru1 Cl2 99.49(6) yes C1 Ru1 Cl2 92.76(6) yes O1 Ru1 Cl2 88.85(4) yes C20 Ru1 Cl1 101.71(6) yes C1 Ru1 Cl1 90.98(6) yes O1 Ru1 Cl1 88.61(4) yes Cl2 Ru1 Cl1 157.668(19) yes C26 O1 C27 118.66(15) ? C26 O1 Ru1 109.48(11) ? C27 O1 Ru1 130.35(12) ? C1 N1 C8 123.76(16) ? C1 N1 C2 111.34(15) ? C8 N1 C2 124.83(15) ? C1 N2 C14 125.94(16) ? C1 N2 C3 111.33(15) ? C14 N2 C3 121.36(15) ? N2 C1 N1 106.23(16) ? N2 C1 Ru1 131.74(14) ? N1 C1 Ru1 121.95(14) ? N1 C2 C4 112.66(16) ? N1 C2 C5 109.07(16) ? C4 C2 C5 110.83(16) ? N1 C2 C3 98.48(14) ? C4 C2 C3 113.27(17) ? C5 C2 C3 111.94(16) ? N2 C3 C7 112.76(16) ? N2 C3 C6 107.12(16) ? C7 C3 C6 109.62(17) ? N2 C3 C2 99.04(15) ? C7 C3 C2 114.45(17) ? C6 C3 C2 113.28(16) ? C13 C8 C9 118.84(18) ? C13 C8 N1 121.79(18) ? C9 C8 N1 119.37(17) ? C10 C9 C8 120.32(19) ? C9 C10 C11 120.8(2) ? C12 C11 C10 118.8(2) ? C13 C12 C11 120.9(2) ? C12 C13 C8 120.4(2) ? C19 C14 C15 120.73(18) ? C19 C14 N2 118.70(17) ? C15 C14 N2 120.56(18) ? C16 C15 C14 118.7(2) ? C17 C16 C15 120.9(2) ? C16 C17 C18 119.9(2) ? C17 C18 C19 120.0(2) ? C14 C19 C18 119.62(19) ? C21 C20 Ru1 120.21(15) ? C26 C21 C22 119.00(18) ? C26 C21 C20 118.30(18) ? C22 C21 C20 122.69(19) ? C23 C22 C21 120.3(2) ? C24 C23 C22 119.6(2) ? C23 C24 C25 121.6(2) ? C24 C25 C26 118.5(2) ? O1 C26 C25 125.62(19) ? O1 C26 C21 113.34(17) ? C25 C26 C21 121.03(19) ? O1 C27 C29 105.82(16) ? O1 C27 C28 109.74(17) ? C29 C27 C28 112.83(19) ? C42 C41 C46 119.9(3) ? C41 C42 C43 120.8(3) ? C42 C43 C44 120.0(3) ? C43 C44 C45 119.8(3) ? C46 C45 C44 119.1(2) ? C41 C46 C45 120.4(2) ? loop_ _geom_bond_atom_site_label_1 _geom_bond_atom_site_label_2 _geom_bond_distance _geom_bond_publ_flag Ru1 C20 1.822(2) yes Ru1 C1 1.959(2) yes Ru1 O1 2.3068(14) yes Ru1 Cl2 2.3354(5) yes Ru1 Cl1 2.3549(5) yes O1 C26 1.376(2) ? O1 C27 1.476(2) ? N1 C1 1.374(2) ? N1 C8 1.419(2) ? N1 C2 1.509(2) ? N2 C1 1.355(2) ? N2 C14 1.438(2) ? N2 C3 1.500(2) ? C2 C4 1.524(3) ? C2 C5 1.536(3) ? C2 C3 1.545(3) ? C3 C7 1.523(3) ? C3 C6 1.530(3) ? C8 C13 1.392(3) ? C8 C9 1.396(3) ? C9 C10 1.387(3) ? C10 C11 1.389(3) ? C11 C12 1.388(3) ? C12 C13 1.386(3) ? C14 C19 1.386(3) ? C14 C15 1.394(3) ? C15 C16 1.393(3) ? C16 C17 1.378(3) ? C17 C18 1.388(3) ? C18 C19 1.392(3) ? C20 C21 1.453(3) ? C21 C26 1.401(3) ? C21 C22 1.401(3) ? C22 C23 1.388(3) ? C23 C24 1.384(3) ? C24 C25 1.391(3) ? C25 C26 1.393(3) ? C27 C29 1.508(3) ? C27 C28 1.517(3) ? C41 C42 1.361(4) ? C41 C46 1.375(4) ? C42 C43 1.368(4) ? C43 C44 1.377(4) ? C44 C45 1.390(4) ? C45 C46 1.383(4) ? _journal_paper_doi 10.1021/ol800824h