#------------------------------------------------------------------------------ #$Date: 2016-03-26 11:46:54 +0000 (Sat, 26 Mar 2016) $ #$Revision: 180235 $ #$URL: svn://www.crystallography.net/cod/cif/7/11/21/7112130.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_7112130 loop_ _publ_author_name 'Mousumi Garai' 'Kumar Biradha' _publ_section_title ; Coordination polymers of organic polymers synthesized via photopolymerization of single crystals: two-dimensional hydrogen bonding layers with amazing shock absorbing nature ; _journal_name_full Chem.Commun. _journal_page_first 3568 _journal_paper_doi 10.1039/C4CC00625A _journal_volume 50 _journal_year 2014 _chemical_formula_sum 'C54 H54 Ag3 Cl3 N12 O18' _chemical_formula_weight 1589.05 _chemical_name_systematic ; ? ; _space_group_IT_number 15 _symmetry_cell_setting monoclinic _symmetry_space_group_name_Hall '-C 2yc' _symmetry_space_group_name_H-M 'C 1 2/c 1' _atom_sites_solution_hydrogens geom _atom_sites_solution_primary direct _atom_sites_solution_secondary difmap _audit_creation_method SHELXL-97 _cell_angle_alpha 90.00 _cell_angle_beta 107.503(2) _cell_angle_gamma 90.00 _cell_formula_units_Z 4 _cell_length_a 20.6773(15) _cell_length_b 9.6611(7) _cell_length_c 30.357(2) _cell_measurement_reflns_used 5391 _cell_measurement_temperature 293(2) _cell_measurement_theta_max 25.50 _cell_measurement_theta_min 1.41 _cell_volume 5783.5(7) _computing_structure_refinement 'SHELXL-97 (Sheldrick, 1997)' _computing_structure_solution 'SHELXS-97 (Sheldrick, 1990)' _diffrn_ambient_temperature 293(2) _diffrn_measured_fraction_theta_full 0.999 _diffrn_measured_fraction_theta_max 0.999 _diffrn_measurement_device_type 'Bruker CCD APEX-2' _diffrn_measurement_method hemisphere _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 0.1099 _diffrn_reflns_av_sigmaI/netI 0.0591 _diffrn_reflns_limit_h_max 24 _diffrn_reflns_limit_h_min -24 _diffrn_reflns_limit_k_max 11 _diffrn_reflns_limit_k_min -11 _diffrn_reflns_limit_l_max 36 _diffrn_reflns_limit_l_min -36 _diffrn_reflns_number 33871 _diffrn_reflns_theta_full 25.50 _diffrn_reflns_theta_max 25.50 _diffrn_reflns_theta_min 1.41 _exptl_absorpt_coefficient_mu 1.230 _exptl_absorpt_correction_T_max 0.878 _exptl_absorpt_correction_T_min 0.838 _exptl_absorpt_correction_type empirical _exptl_absorpt_process_details sadabs _exptl_crystal_colour 'light yellow' _exptl_crystal_density_diffrn 1.825 _exptl_crystal_density_method 'not measured' _exptl_crystal_description 'rectangular block' _exptl_crystal_F_000 3192 _exptl_crystal_size_max 0.23 _exptl_crystal_size_mid 0.12 _exptl_crystal_size_min 0.11 _refine_diff_density_max 1.665 _refine_diff_density_min -1.303 _refine_diff_density_rms 0.125 _refine_ls_extinction_method none _refine_ls_goodness_of_fit_ref 1.161 _refine_ls_hydrogen_treatment mixed _refine_ls_matrix_type full _refine_ls_number_parameters 408 _refine_ls_number_reflns 5391 _refine_ls_number_restraints 0 _refine_ls_restrained_S_all 1.161 _refine_ls_R_factor_all 0.0931 _refine_ls_R_factor_gt 0.0605 _refine_ls_shift/su_max 0.001 _refine_ls_shift/su_mean 0.000 _refine_ls_structure_factor_coef Fsqd _refine_ls_weighting_details 'calc w=1/[\s^2^(Fo^2^)+(0.1000P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3' _refine_ls_weighting_scheme calc _refine_ls_wR_factor_gt 0.1649 _refine_ls_wR_factor_ref 0.1776 _reflns_number_gt 3877 _reflns_number_total 5391 _reflns_threshold_expression >2sigma(I) _cod_data_source_file c4cc00625a.cif _cod_data_source_block 2' _cod_original_sg_symbol_H-M C2/c _cod_database_code 7112130 loop_ _symmetry_equiv_pos_as_xyz 'x, y, z' '-x, y, -z+1/2' 'x+1/2, y+1/2, z' '-x+1/2, y+1/2, -z+1/2' '-x, -y, -z' 'x, -y, z-1/2' '-x+1/2, -y+1/2, -z' 'x+1/2, -y+1/2, z-1/2' 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 Ag1 Ag 0.5000 0.5000 0.0000 0.0477(3) Uani 1 2 d S Ag2 Ag 0.99134(3) 1.02512(6) 0.338721(17) 0.0516(2) Uani 1 1 d . Cl1 Cl 0.92984(8) 0.77496(16) 0.40390(5) 0.0401(4) Uani 1 1 d . O101 O 0.9088(2) 0.7781(5) 0.44512(14) 0.0543(13) Uani 1 1 d . O102 O 0.9999(3) 0.8126(8) 0.41515(16) 0.0770(19) Uani 1 1 d . O103 O 0.8893(3) 0.8701(5) 0.37077(15) 0.0566(14) Uani 1 1 d . O104 O 0.9227(3) 0.6384(5) 0.38545(18) 0.0666(15) Uani 1 1 d . Cl2 Cl 1.0000 1.2630(3) 0.2500 0.1049(15) Uani 1 2 d S O201 O 1.0454(8) 1.1987(18) 0.2386(7) 0.47(2) Uani 1 1 d . O202 O 0.9607(4) 1.3450(8) 0.2129(2) 0.101(2) Uani 1 1 d . O21A O 0.7503(2) 0.9176(4) 0.42168(13) 0.0356(10) Uani 1 1 d . O11A O 0.7289(2) 0.5642(4) 0.22859(13) 0.0412(11) Uani 1 1 d . O11B O 0.7997(2) 0.9089(4) 0.09259(13) 0.0366(10) Uani 1 1 d . N11A N 0.5684(2) 0.6639(5) 0.03383(15) 0.0364(12) Uani 1 1 d . C11A C 0.6594(3) 0.7355(5) 0.10070(17) 0.0252(12) Uani 1 1 d . C12A C 0.6193(3) 0.6341(6) 0.07154(18) 0.0304(13) Uani 1 1 d . H12A H 0.6290 0.5415 0.0790 0.036 Uiso 1 1 calc R C13A C 0.5550(3) 0.7982(6) 0.02251(19) 0.0357(14) Uani 1 1 d . H13A H 0.5200 0.8204 -0.0039 0.043 Uiso 1 1 calc R C14A C 0.5918(3) 0.9024(6) 0.04904(18) 0.0341(14) Uani 1 1 d . H14A H 0.5817 0.9940 0.0403 0.041 Uiso 1 1 calc R C15A C 0.6435(3) 0.8728(6) 0.08842(18) 0.0294(13) Uani 1 1 d . H15A H 0.6678 0.9439 0.1067 0.035 Uiso 1 1 calc R C16A C 0.7159(3) 0.6882(5) 0.14150(17) 0.0257(12) Uani 1 1 d . H16A H 0.7099 0.5905 0.1479 0.031 Uiso 1 1 calc R C17A C 0.7317(3) 0.7742(5) 0.18666(16) 0.0204(11) Uani 1 1 d . H17A H 0.7035 0.8575 0.1830 0.024 Uiso 1 1 calc R C18A C 0.7316(3) 0.6910(5) 0.22908(17) 0.0241(11) Uani 1 1 d . N21A N 0.5376(2) 0.6785(5) 0.39007(16) 0.0358(12) Uani 1 1 d . C21A C 0.6337(3) 0.7420(5) 0.45458(16) 0.0258(12) Uani 1 1 d . C22A C 0.5937(3) 0.6454(6) 0.42437(17) 0.0282(12) Uani 1 1 d . H22A H 0.6065 0.5529 0.4282 0.034 Uiso 1 1 calc R C23A C 0.5182(3) 0.8108(7) 0.3854(2) 0.0393(15) Uani 1 1 d . H23A H 0.4798 0.8347 0.3614 0.047 Uiso 1 1 calc R C24A C 0.5528(3) 0.9139(7) 0.4148(2) 0.0447(16) Uani 1 1 d . H24A H 0.5370 1.0046 0.4115 0.054 Uiso 1 1 calc R C25A C 0.6116(3) 0.8788(6) 0.44914(18) 0.0318(13) Uani 1 1 d . H25A H 0.6364 0.9469 0.4687 0.038 Uiso 1 1 calc R C26A C 0.7001(3) 0.6964(5) 0.48742(16) 0.0230(11) Uani 1 1 d . H26A H 0.6968 0.6000 0.4966 0.028 Uiso 1 1 calc R C27A C 0.7641(3) 0.7150(5) 0.46955(16) 0.0212(11) Uani 1 1 d . H27A H 0.7877 0.6273 0.4689 0.025 Uiso 1 1 calc R C28A C 0.7480(3) 0.7920(5) 0.42391(16) 0.0233(11) Uani 1 1 d . N31A N 0.7380(2) 0.7661(5) 0.26688(14) 0.0294(11) Uani 1 1 d . H31A H 0.7351 0.8548 0.2645 0.035 Uiso 1 1 calc R N32A N 0.7297(2) 0.7097(5) 0.38649(14) 0.0324(11) Uani 1 1 d . H32A H 0.7294 0.6214 0.3902 0.039 Uiso 1 1 calc R C31A C 0.7497(4) 0.7022(7) 0.31228(19) 0.0423(16) Uani 1 1 d . H31B H 0.7975 0.7092 0.3293 0.051 Uiso 1 1 calc . H31C H 0.7382 0.6048 0.3083 0.051 Uiso 1 1 calc . C32A C 0.7101(4) 0.7666(8) 0.33894(18) 0.0505(19) Uani 1 1 d . H32B H 0.6623 0.7500 0.3240 0.061 Uiso 1 1 calc . H32C H 0.7176 0.8659 0.3402 0.061 Uiso 1 1 calc . N11B N 0.9519(3) 0.8605(6) 0.29025(16) 0.0412(13) Uani 1 1 d . C11B C 0.8650(3) 0.7745(5) 0.22407(17) 0.0246(12) Uani 1 1 d . C12B C 0.8999(3) 0.8799(6) 0.25150(19) 0.0329(14) Uani 1 1 d . H12B H 0.8868 0.9704 0.2427 0.039 Uiso 1 1 calc R C13B C 0.9710(3) 0.7283(7) 0.3023(2) 0.0445(17) Uani 1 1 d . H13B H 1.0070 0.7125 0.3289 0.053 Uiso 1 1 calc R C14B C 0.9395(4) 0.6179(7) 0.2770(2) 0.0486(18) Uani 1 1 d . H14B H 0.9543 0.5284 0.2861 0.058 Uiso 1 1 calc R C15B C 0.8853(3) 0.6392(6) 0.23760(19) 0.0372(15) Uani 1 1 d . H15B H 0.8628 0.5644 0.2204 0.045 Uiso 1 1 calc R C16B C 0.8051(3) 0.8066(5) 0.18347(16) 0.0229(11) Uani 1 1 d . H16B H 0.8073 0.9036 0.1746 0.027 Uiso 1 1 calc R C17B C 0.7900(3) 0.7146(5) 0.14015(16) 0.0200(11) Uani 1 1 d . H17B H 0.8169 0.6293 0.1465 0.024 Uiso 1 1 calc R C18B C 0.7947(3) 0.7849(5) 0.09587(17) 0.0256(12) Uani 1 1 d . N21B N 0.7902(2) 0.6955(5) 0.06150(14) 0.0313(11) Uani 1 1 d . H21B H 0.7899 0.6082 0.0670 0.038 Uiso 1 1 calc R C21B C 0.7860(3) 0.7414(6) 0.01504(18) 0.0343(14) Uani 1 1 d . H21A H 0.8086 0.6744 0.0010 0.041 Uiso 1 1 calc . H21C H 0.8096 0.8290 0.0169 0.041 Uiso 1 1 calc . 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 Ag1 0.0457(4) 0.0432(4) 0.0399(4) -0.0093(3) -0.0086(3) -0.0139(3) Ag2 0.0531(4) 0.0599(4) 0.0308(3) -0.0118(2) -0.0042(2) -0.0213(3) Cl1 0.0472(9) 0.0397(9) 0.0300(7) 0.0054(6) 0.0066(7) 0.0022(7) O101 0.053(3) 0.080(4) 0.031(2) 0.009(2) 0.013(2) 0.008(3) O102 0.054(3) 0.127(6) 0.047(3) 0.016(3) 0.010(3) -0.029(3) O103 0.081(4) 0.047(3) 0.036(2) 0.008(2) 0.009(2) 0.025(3) O104 0.102(4) 0.037(3) 0.062(3) 0.005(2) 0.025(3) 0.006(3) Cl2 0.177(4) 0.0342(16) 0.087(3) 0.000 0.014(3) 0.000 O201 0.36(2) 0.43(2) 0.40(2) -0.32(2) -0.23(2) 0.33(2) O202 0.105(5) 0.124(6) 0.056(4) 0.002(4) -0.003(4) -0.010(5) O21A 0.047(3) 0.029(2) 0.031(2) 0.0057(17) 0.0123(18) 0.0050(18) O11A 0.067(3) 0.024(2) 0.033(2) 0.0008(17) 0.016(2) -0.008(2) O11B 0.054(3) 0.027(2) 0.032(2) 0.0010(17) 0.0184(19) -0.0055(19) N11A 0.034(3) 0.037(3) 0.027(2) -0.008(2) -0.007(2) -0.006(2) C11A 0.029(3) 0.027(3) 0.019(2) -0.004(2) 0.005(2) -0.006(2) C12A 0.029(3) 0.029(3) 0.027(3) 0.001(2) -0.001(2) -0.006(2) C13A 0.036(3) 0.035(3) 0.028(3) -0.002(2) -0.003(3) 0.001(3) C14A 0.038(3) 0.031(3) 0.030(3) -0.001(2) 0.005(3) 0.004(3) C15A 0.032(3) 0.027(3) 0.026(3) -0.006(2) 0.006(2) -0.001(2) C16A 0.039(3) 0.020(3) 0.018(2) -0.001(2) 0.008(2) -0.003(2) C17A 0.021(3) 0.023(3) 0.016(2) -0.0017(19) 0.004(2) -0.001(2) C18A 0.024(3) 0.025(3) 0.024(3) -0.001(2) 0.009(2) -0.003(2) N21A 0.031(3) 0.043(3) 0.028(2) -0.003(2) 0.001(2) -0.008(2) C21A 0.036(3) 0.029(3) 0.014(2) -0.005(2) 0.011(2) -0.008(2) C22A 0.029(3) 0.033(3) 0.023(3) -0.004(2) 0.008(2) -0.005(2) C23A 0.022(3) 0.060(4) 0.032(3) 0.004(3) 0.003(2) 0.002(3) C24A 0.046(4) 0.042(4) 0.042(4) -0.003(3) 0.008(3) 0.010(3) C25A 0.033(3) 0.035(3) 0.026(3) -0.007(2) 0.006(2) -0.002(3) C26A 0.031(3) 0.020(2) 0.017(2) -0.0030(19) 0.007(2) -0.007(2) C27A 0.029(3) 0.020(3) 0.013(2) -0.0027(19) 0.002(2) -0.002(2) C28A 0.023(3) 0.030(3) 0.019(2) 0.004(2) 0.009(2) 0.003(2) N31A 0.046(3) 0.026(2) 0.016(2) 0.0023(17) 0.011(2) -0.001(2) N32A 0.047(3) 0.037(3) 0.012(2) 0.0055(19) 0.008(2) 0.013(2) C31A 0.060(4) 0.052(4) 0.020(3) 0.004(3) 0.019(3) 0.002(3) C32A 0.068(5) 0.077(5) 0.009(3) 0.009(3) 0.014(3) 0.030(4) N11B 0.038(3) 0.054(3) 0.025(2) -0.010(2) 0.000(2) -0.012(3) C11B 0.030(3) 0.028(3) 0.017(2) -0.002(2) 0.009(2) -0.002(2) C12B 0.028(3) 0.036(3) 0.029(3) -0.001(2) 0.001(2) -0.009(2) C13B 0.030(3) 0.073(5) 0.024(3) 0.000(3) -0.002(3) 0.005(3) C14B 0.063(5) 0.042(4) 0.031(3) 0.003(3) -0.001(3) 0.017(3) C15B 0.043(4) 0.036(3) 0.026(3) -0.009(2) 0.000(3) 0.005(3) C16B 0.037(3) 0.017(2) 0.016(2) -0.0035(19) 0.010(2) -0.004(2) C17B 0.024(3) 0.020(3) 0.015(2) -0.0004(19) 0.005(2) 0.000(2) C18B 0.029(3) 0.028(3) 0.020(3) 0.003(2) 0.007(2) 0.001(2) N21B 0.053(3) 0.025(2) 0.017(2) 0.0013(18) 0.011(2) 0.005(2) C21B 0.048(4) 0.037(3) 0.022(3) 0.000(2) 0.017(3) -0.003(3) 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' Ag Ag -0.8971 1.1015 '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_site_symmetry_1 _geom_angle_site_symmetry_3 N11A Ag1 N11A 180.0(2) 5_665 . N21A Ag2 N11B 175.25(19) 3 . O104 Cl1 O103 110.4(3) . . O104 Cl1 O102 107.9(4) . . O103 Cl1 O102 109.9(4) . . O104 Cl1 O101 109.7(3) . . O103 Cl1 O101 109.3(3) . . O102 Cl1 O101 109.6(3) . . O201 Cl2 O201 121(2) 2_755 . O201 Cl2 O202 110.7(11) 2_755 2_755 O201 Cl2 O202 101.4(6) . 2_755 O201 Cl2 O202 101.4(6) 2_755 . O201 Cl2 O202 110.7(11) . . O202 Cl2 O202 112.0(6) 2_755 . C12A N11A C13A 118.3(5) . . C12A N11A Ag1 119.0(4) . . C13A N11A Ag1 121.9(4) . . C15A C11A C12A 116.6(5) . . C15A C11A C16A 125.2(5) . . C12A C11A C16A 118.3(5) . . N11A C12A C11A 123.6(5) . . N11A C13A C14A 121.5(5) . . C13A C14A C15A 120.6(5) . . C14A C15A C11A 119.4(5) . . C11A C16A C17A 118.2(4) . . C11A C16A C17B 117.1(4) . . C17A C16A C17B 89.3(4) . . C18A C17A C16A 114.4(4) . . C18A C17A C16B 113.7(4) . . C16A C17A C16B 90.1(4) . . O11A C18A N31A 123.2(5) . . O11A C18A C17A 122.0(5) . . N31A C18A C17A 114.7(4) . . C23A N21A C22A 118.1(5) . . C23A N21A Ag2 121.9(4) . 3_445 C22A N21A Ag2 119.3(4) . 3_445 C22A C21A C25A 116.7(5) . . C22A C21A C26A 119.0(5) . . C25A C21A C26A 124.1(5) . . N21A C22A C21A 123.7(5) . . N21A C23A C24A 122.7(5) . . C23A C24A C25A 118.4(6) . . C24A C25A C21A 120.3(5) . . C21A C26A C27A 120.5(4) . 7_666 C21A C26A C27A 115.5(4) . . C27A C26A C27A 89.4(4) 7_666 . C28A C27A C26A 114.6(4) . 7_666 C28A C27A C26A 113.0(4) . . C26A C27A C26A 90.6(4) 7_666 . O21A C28A N32A 123.3(5) . . O21A C28A C27A 122.5(5) . . N32A C28A C27A 114.2(5) . . C18A N31A C31A 121.9(5) . . C28A N32A C32A 121.9(5) . . N31A C31A C32A 112.5(5) . . C31A C32A N32A 110.4(5) . . C12B N11B C13B 117.4(5) . . C12B N11B Ag2 122.2(4) . . C13B N11B Ag2 119.4(4) . . C12B C11B C15B 117.3(5) . . C12B C11B C16B 120.0(5) . . C15B C11B C16B 122.6(5) . . N11B C12B C11B 124.1(6) . . N11B C13B C14B 122.3(5) . . C13B C14B C15B 119.7(6) . . C14B C15B C11B 119.1(5) . . C11B C16B C17B 119.3(4) . . C11B C16B C17A 118.8(4) . . C17B C16B C17A 89.2(4) . . C18B C17B C16B 116.3(4) . . C18B C17B C16A 114.5(4) . . C16B C17B C16A 91.1(4) . . O11B C18B N21B 124.3(5) . . O11B C18B C17B 122.7(5) . . N21B C18B C17B 113.0(4) . . C18B N21B C21B 122.0(5) . . N21B C21B C21B 112.5(6) . 7_665 loop_ _geom_bond_atom_site_label_1 _geom_bond_atom_site_label_2 _geom_bond_distance _geom_bond_site_symmetry_2 Ag1 N11A 2.165(4) 5_665 Ag1 N11A 2.165(4) . Ag2 N21A 2.155(5) 3 Ag2 N11B 2.154(5) . Cl1 O104 1.423(5) . Cl1 O103 1.432(4) . Cl1 O102 1.431(5) . Cl1 O101 1.444(5) . Cl2 O201 1.258(15) 2_755 Cl2 O201 1.258(15) . Cl2 O202 1.417(7) 2_755 Cl2 O202 1.417(7) . O21A C28A 1.218(6) . O11A C18A 1.226(6) . O11B C18B 1.209(6) . N11A C12A 1.333(7) . N11A C13A 1.350(7) . C11A C15A 1.390(7) . C11A C12A 1.410(7) . C11A C16A 1.495(7) . C13A C14A 1.368(8) . C14A C15A 1.373(7) . C16A C17A 1.551(6) . C16A C17B 1.566(7) . C17A C18A 1.518(7) . C17A C16B 1.581(7) . C18A N31A 1.330(7) . N21A C23A 1.334(8) . N21A C22A 1.343(7) . N21A Ag2 2.155(5) 3_445 C21A C22A 1.393(7) . C21A C25A 1.392(8) . C21A C26A 1.500(7) . C23A C24A 1.384(9) . C24A C25A 1.384(8) . C26A C27A 1.551(6) 7_666 C26A C27A 1.586(8) . C27A C28A 1.519(6) . C27A C26A 1.551(6) 7_666 C28A N32A 1.345(7) . N31A C31A 1.462(7) . N32A C32A 1.483(6) . C31A C32A 1.453(9) . N11B C12B 1.347(7) . N11B C13B 1.354(8) . C11B C12B 1.375(7) . C11B C15B 1.396(8) . C11B C16B 1.494(7) . C13B C14B 1.361(9) . C14B C15B 1.387(8) . C16B C17B 1.539(6) . C17B C18B 1.535(7) . C18B N21B 1.336(7) . N21B C21B 1.456(7) . C21B C21B 1.503(12) 7_665