# Electronic Supplementary Material (ESI) for Organdic and Biomolecular Chemistry # This journal is © The Royal Society of Chemistry 2011 data_global _journal_name_full Org.Biomol.Chem. _journal_coden_cambridge 0177 _journal_year ? _journal_volume ? _journal_page_first ? loop_ _publ_author_name 'Fang-gang Sun' 'Song Ye' _publ_contact_author_name 'Song Ye' _publ_contact_author_email songye@iccas.ac.cn data_sx2891 _database_code_depnum_ccdc_archive 'CCDC 807044' #TrackingRef 'sx2891.cif' _audit_creation_method SHELXL-97 _chemical_name_systematic ; ? ; _chemical_name_common ? _chemical_melting_point ? _chemical_formula_moiety 'C20 H21 N O4' _chemical_formula_sum 'C20 H21 N O4' _chemical_formula_weight 339.38 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' _symmetry_cell_setting monoclinic _symmetry_space_group_name_H-M P2(1)/n loop_ _symmetry_equiv_pos_as_xyz 'x, y, z' '-x+1/2, y+1/2, -z+1/2' '-x, -y, -z' 'x-1/2, -y-1/2, z-1/2' _cell_length_a 10.1977(15) _cell_length_b 16.971(3) _cell_length_c 11.0473(17) _cell_angle_alpha 90.00 _cell_angle_beta 113.378(10) _cell_angle_gamma 90.00 _cell_volume 1754.9(5) _cell_formula_units_Z 4 _cell_measurement_temperature 173(2) _cell_measurement_reflns_used 435 _cell_measurement_theta_min 3.12 _cell_measurement_theta_max 68.22 _exptl_crystal_description block _exptl_crystal_colour colorless _exptl_crystal_size_max 0.55 _exptl_crystal_size_mid 0.50 _exptl_crystal_size_min 0.40 _exptl_crystal_density_meas ? _exptl_crystal_density_diffrn 1.285 _exptl_crystal_density_method 'not measured' _exptl_crystal_F_000 720 _exptl_absorpt_coefficient_mu 0.730 _exptl_absorpt_correction_type numerical _exptl_absorpt_correction_T_min 0.6897 _exptl_absorpt_correction_T_max 0.7590 _exptl_absorpt_process_details 'NUMABS by T.Higashi Jun 3, 2003' _exptl_special_details ; ? ; _diffrn_ambient_temperature 173(2) _diffrn_radiation_wavelength 1.54186 _diffrn_radiation_type CuK\a _diffrn_radiation_source 'rotating anode' _diffrn_radiation_monochromator graphite _diffrn_measurement_device_type 'Rigaku raxis Rapid IP Area Detector' _diffrn_measurement_method '\w scans' _diffrn_detector_area_resol_mean ? _diffrn_standards_number ? _diffrn_standards_interval_count ? _diffrn_standards_interval_time ? _diffrn_standards_decay_% ? _diffrn_reflns_number 12122 _diffrn_reflns_av_R_equivalents 0.0309 _diffrn_reflns_av_sigmaI/netI 0.0306 _diffrn_reflns_limit_h_min -12 _diffrn_reflns_limit_h_max 12 _diffrn_reflns_limit_k_min -18 _diffrn_reflns_limit_k_max 20 _diffrn_reflns_limit_l_min -11 _diffrn_reflns_limit_l_max 13 _diffrn_reflns_theta_min 5.00 _diffrn_reflns_theta_max 68.23 _reflns_number_total 3154 _reflns_number_gt 2651 _reflns_threshold_expression >2sigma(I) _computing_data_collection 'Rapid Auto Ver 2.30(Rigaku 1998)' _computing_cell_refinement 'Rapid Auto Ver 2.30(Rigaku 1998)' _computing_data_reduction 'Rapid Auto Ver 2.30(Rigaku 1998)' _computing_structure_solution 'SHELXS-97 (Sheldrick, 1990)' _computing_structure_refinement 'SHELXL-97 (Sheldrick, 1997)' _computing_molecular_graphics 'XP in Siemens SHELXTL (Sheldrick, 1994)' _computing_publication_material 'SHELX97 (Sheldrick, 1997)' _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^)+(0.0427P)^2^+0.5825P] 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 constr _refine_ls_extinction_method SHELXL _refine_ls_extinction_coef 0.0018(2) _refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^ _refine_ls_number_reflns 3154 _refine_ls_number_parameters 230 _refine_ls_number_restraints 0 _refine_ls_R_factor_all 0.0441 _refine_ls_R_factor_gt 0.0371 _refine_ls_wR_factor_ref 0.0994 _refine_ls_wR_factor_gt 0.0962 _refine_ls_goodness_of_fit_ref 1.071 _refine_ls_restrained_S_all 1.071 _refine_ls_shift/su_max 0.000 _refine_ls_shift/su_mean 0.000 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 0.24089(11) 0.13724(7) 0.56294(11) 0.0351(3) Uani 1 1 d . . . O2 O 0.65752(11) 0.03598(6) 0.73787(11) 0.0303(3) Uani 1 1 d . . . H2A H 0.5840 0.0084 0.7003 0.045 Uiso 1 1 calc R . . O3 O 0.59084(12) 0.05224(7) 0.38658(11) 0.0338(3) Uani 1 1 d . . . O4 O 0.70672(10) 0.14484(6) 0.54103(10) 0.0275(3) Uani 1 1 d . . . N1 N 0.48588(13) 0.11112(8) 0.50960(12) 0.0259(3) Uani 1 1 d . . . H1A H 0.4007 0.0943 0.4567 0.031 Uiso 1 1 calc R . . C1 C 0.54612(16) 0.11284(9) 0.85551(15) 0.0259(3) Uani 1 1 d . . . C2 C 0.60910(17) 0.10022(10) 0.99050(16) 0.0309(4) Uani 1 1 d . . . H2B H 0.7099 0.0956 1.0347 0.037 Uiso 1 1 calc R . . C3 C 0.52187(19) 0.09454(10) 1.05948(17) 0.0347(4) Uani 1 1 d . . . H3A H 0.5636 0.0865 1.1522 0.042 Uiso 1 1 calc R . . C4 C 0.37335(18) 0.10047(10) 0.99475(17) 0.0344(4) Uani 1 1 d . . . H4A H 0.3154 0.0949 1.0436 0.041 Uiso 1 1 calc R . . C5 C 0.31021(17) 0.11426(10) 0.86111(16) 0.0317(4) Uani 1 1 d . . . H5A H 0.2094 0.1189 0.8170 0.038 Uiso 1 1 calc R . . C6 C 0.39863(16) 0.12123(9) 0.79220(15) 0.0260(3) Uani 1 1 d . . . C7 C 0.35897(15) 0.13609(9) 0.65113(15) 0.0263(3) Uani 1 1 d . . . C8 C 0.49960(15) 0.15037(9) 0.63069(14) 0.0241(3) Uani 1 1 d . . . C9 C 0.61708(15) 0.11308(9) 0.75800(15) 0.0249(3) Uani 1 1 d . . . H9A H 0.7032 0.1479 0.7913 0.030 Uiso 1 1 calc R . . C10 C 0.59623(15) 0.09876(9) 0.47306(15) 0.0249(3) Uani 1 1 d . . . C11 C 0.84778(16) 0.13604(10) 0.53374(16) 0.0302(4) Uani 1 1 d . . . C12 C 0.90764(18) 0.05543(10) 0.58680(19) 0.0412(4) Uani 1 1 d . . . H12A H 0.9017 0.0471 0.6723 0.062 Uiso 1 1 calc R . . H12B H 1.0077 0.0525 0.5977 0.062 Uiso 1 1 calc R . . H12C H 0.8522 0.0147 0.5247 0.062 Uiso 1 1 calc R . . C13 C 0.8376(2) 0.14978(14) 0.39491(19) 0.0532(6) Uani 1 1 d . . . H13A H 0.7813 0.1974 0.3588 0.080 Uiso 1 1 calc R . . H13B H 0.7911 0.1045 0.3395 0.080 Uiso 1 1 calc R . . H13C H 0.9338 0.1564 0.3965 0.080 Uiso 1 1 calc R . . C14 C 0.93267(17) 0.20101(10) 0.62505(18) 0.0372(4) Uani 1 1 d . . . H14A H 0.9425 0.1895 0.7152 0.056 Uiso 1 1 calc R . . H14B H 0.8828 0.2513 0.5963 0.056 Uiso 1 1 calc R . . H14C H 1.0276 0.2043 0.6228 0.056 Uiso 1 1 calc R . . C15 C 0.51933(15) 0.23999(9) 0.62483(15) 0.0248(3) Uani 1 1 d . . . C16 C 0.47042(16) 0.27857(10) 0.50362(15) 0.0298(4) Uani 1 1 d . . . H16A H 0.4229 0.2494 0.4248 0.036 Uiso 1 1 calc R . . C17 C 0.49032(17) 0.35886(10) 0.49671(17) 0.0335(4) Uani 1 1 d . . . H17A H 0.4570 0.3842 0.4132 0.040 Uiso 1 1 calc R . . C18 C 0.55844(17) 0.40261(10) 0.61042(17) 0.0341(4) Uani 1 1 d . . . H18A H 0.5736 0.4575 0.6054 0.041 Uiso 1 1 calc R . . C19 C 0.60404(17) 0.36507(10) 0.73118(17) 0.0333(4) Uani 1 1 d . . . H19A H 0.6494 0.3946 0.8099 0.040 Uiso 1 1 calc R . . C20 C 0.58418(16) 0.28481(10) 0.73849(15) 0.0290(4) Uani 1 1 d . . . H20A H 0.6153 0.2600 0.8223 0.035 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 0.0224(5) 0.0516(8) 0.0283(6) -0.0001(5) 0.0068(5) -0.0009(5) O2 0.0286(5) 0.0286(6) 0.0344(6) -0.0005(5) 0.0133(5) 0.0037(5) O3 0.0370(6) 0.0365(7) 0.0333(6) -0.0108(5) 0.0197(5) -0.0063(5) O4 0.0250(5) 0.0282(6) 0.0319(6) -0.0039(5) 0.0141(5) -0.0033(4) N1 0.0223(6) 0.0314(7) 0.0237(7) -0.0049(6) 0.0088(5) -0.0031(5) C1 0.0290(8) 0.0234(8) 0.0256(8) -0.0010(6) 0.0111(6) -0.0007(6) C2 0.0313(8) 0.0302(9) 0.0281(9) 0.0006(7) 0.0084(7) 0.0001(7) C3 0.0465(10) 0.0340(9) 0.0241(8) 0.0004(7) 0.0147(7) -0.0009(8) C4 0.0426(9) 0.0347(9) 0.0337(9) -0.0006(8) 0.0234(8) -0.0014(8) C5 0.0312(8) 0.0340(9) 0.0334(9) -0.0016(7) 0.0164(7) -0.0009(7) C6 0.0274(7) 0.0255(8) 0.0255(8) -0.0010(6) 0.0109(6) -0.0011(6) C7 0.0246(7) 0.0275(8) 0.0276(8) -0.0021(7) 0.0113(6) -0.0002(6) C8 0.0220(7) 0.0287(8) 0.0221(8) -0.0023(6) 0.0092(6) -0.0012(6) C9 0.0233(7) 0.0256(8) 0.0251(8) -0.0018(6) 0.0089(6) -0.0007(6) C10 0.0262(7) 0.0243(8) 0.0246(8) 0.0005(6) 0.0105(6) -0.0021(6) C11 0.0239(7) 0.0367(9) 0.0343(9) -0.0008(7) 0.0161(7) -0.0043(7) C12 0.0356(9) 0.0349(10) 0.0540(12) -0.0066(9) 0.0188(8) 0.0028(8) C13 0.0459(10) 0.0838(16) 0.0367(11) 0.0007(11) 0.0237(9) -0.0171(11) C14 0.0304(8) 0.0357(10) 0.0450(10) 0.0008(8) 0.0144(7) -0.0049(7) C15 0.0201(7) 0.0293(8) 0.0262(8) -0.0010(7) 0.0106(6) 0.0006(6) C16 0.0292(8) 0.0321(9) 0.0237(8) -0.0011(7) 0.0059(6) -0.0001(7) C17 0.0364(8) 0.0326(9) 0.0276(9) 0.0049(7) 0.0086(7) 0.0014(7) C18 0.0357(9) 0.0280(9) 0.0378(10) 0.0007(7) 0.0137(7) -0.0004(7) C19 0.0365(9) 0.0312(9) 0.0293(9) -0.0059(7) 0.0100(7) -0.0022(7) C20 0.0315(8) 0.0307(9) 0.0242(8) -0.0006(7) 0.0104(6) 0.0006(7) _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 C7 1.2118(18) . ? O2 C9 1.4158(18) . ? O2 H2A 0.8400 . ? O3 C10 1.2237(18) . ? O4 C10 1.3317(18) . ? O4 C11 1.4799(17) . ? N1 C10 1.3542(19) . ? N1 C8 1.4506(19) . ? N1 H1A 0.8800 . ? C1 C2 1.386(2) . ? C1 C6 1.392(2) . ? C1 C9 1.517(2) . ? C2 C3 1.385(2) . ? C2 H2B 0.9500 . ? C3 C4 1.398(2) . ? C3 H3A 0.9500 . ? C4 C5 1.376(2) . ? C4 H4A 0.9500 . ? C5 C6 1.397(2) . ? C5 H5A 0.9500 . ? C6 C7 1.468(2) . ? C7 C8 1.5567(19) . ? C8 C15 1.539(2) . ? C8 C9 1.574(2) . ? C9 H9A 1.0000 . ? C11 C14 1.513(2) . ? C11 C13 1.514(2) . ? C11 C12 1.518(2) . ? C12 H12A 0.9800 . ? C12 H12B 0.9800 . ? C12 H12C 0.9800 . ? C13 H13A 0.9800 . ? C13 H13B 0.9800 . ? C13 H13C 0.9800 . ? C14 H14A 0.9800 . ? C14 H14B 0.9800 . ? C14 H14C 0.9800 . ? C15 C20 1.390(2) . ? C15 C16 1.393(2) . ? C16 C17 1.384(2) . ? C16 H16A 0.9500 . ? C17 C18 1.385(2) . ? C17 H17A 0.9500 . ? C18 C19 1.382(2) . ? C18 H18A 0.9500 . ? C19 C20 1.384(2) . ? C19 H19A 0.9500 . ? C20 H20A 0.9500 . ? 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 C9 O2 H2A 109.5 . . ? C10 O4 C11 122.22(12) . . ? C10 N1 C8 123.96(12) . . ? C10 N1 H1A 118.0 . . ? C8 N1 H1A 118.0 . . ? C2 C1 C6 120.22(14) . . ? C2 C1 C9 128.04(14) . . ? C6 C1 C9 111.57(13) . . ? C3 C2 C1 118.55(15) . . ? C3 C2 H2B 120.7 . . ? C1 C2 H2B 120.7 . . ? C2 C3 C4 121.01(15) . . ? C2 C3 H3A 119.5 . . ? C4 C3 H3A 119.5 . . ? C5 C4 C3 120.76(15) . . ? C5 C4 H4A 119.6 . . ? C3 C4 H4A 119.6 . . ? C4 C5 C6 118.07(15) . . ? C4 C5 H5A 121.0 . . ? C6 C5 H5A 121.0 . . ? C1 C6 C5 121.34(15) . . ? C1 C6 C7 109.79(13) . . ? C5 C6 C7 128.87(14) . . ? O1 C7 C6 128.57(14) . . ? O1 C7 C8 124.03(14) . . ? C6 C7 C8 107.41(12) . . ? N1 C8 C15 112.43(12) . . ? N1 C8 C7 107.76(11) . . ? C15 C8 C7 107.65(11) . . ? N1 C8 C9 113.59(12) . . ? C15 C8 C9 111.66(12) . . ? C7 C8 C9 103.07(11) . . ? O2 C9 C1 111.08(12) . . ? O2 C9 C8 113.40(12) . . ? C1 C9 C8 103.13(11) . . ? O2 C9 H9A 109.7 . . ? C1 C9 H9A 109.7 . . ? C8 C9 H9A 109.7 . . ? O3 C10 O4 125.81(13) . . ? O3 C10 N1 123.19(13) . . ? O4 C10 N1 110.99(13) . . ? O4 C11 C14 101.63(12) . . ? O4 C11 C13 111.24(13) . . ? C14 C11 C13 110.75(14) . . ? O4 C11 C12 108.70(12) . . ? C14 C11 C12 111.30(14) . . ? C13 C11 C12 112.68(16) . . ? C11 C12 H12A 109.5 . . ? C11 C12 H12B 109.5 . . ? H12A C12 H12B 109.5 . . ? C11 C12 H12C 109.5 . . ? H12A C12 H12C 109.5 . . ? H12B C12 H12C 109.5 . . ? C11 C13 H13A 109.5 . . ? C11 C13 H13B 109.5 . . ? H13A C13 H13B 109.5 . . ? C11 C13 H13C 109.5 . . ? H13A C13 H13C 109.5 . . ? H13B C13 H13C 109.5 . . ? C11 C14 H14A 109.5 . . ? C11 C14 H14B 109.5 . . ? H14A C14 H14B 109.5 . . ? C11 C14 H14C 109.5 . . ? H14A C14 H14C 109.5 . . ? H14B C14 H14C 109.5 . . ? C20 C15 C16 118.13(14) . . ? C20 C15 C8 121.73(14) . . ? C16 C15 C8 120.13(13) . . ? C17 C16 C15 120.74(15) . . ? C17 C16 H16A 119.6 . . ? C15 C16 H16A 119.6 . . ? C16 C17 C18 120.62(16) . . ? C16 C17 H17A 119.7 . . ? C18 C17 H17A 119.7 . . ? C19 C18 C17 118.94(16) . . ? C19 C18 H18A 120.5 . . ? C17 C18 H18A 120.5 . . ? C18 C19 C20 120.59(15) . . ? C18 C19 H19A 119.7 . . ? C20 C19 H19A 119.7 . . ? C19 C20 C15 120.92(15) . . ? C19 C20 H20A 119.5 . . ? C15 C20 H20A 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_site_symmetry_1 _geom_torsion_site_symmetry_2 _geom_torsion_site_symmetry_3 _geom_torsion_site_symmetry_4 _geom_torsion_publ_flag C6 C1 C2 C3 1.4(2) . . . . ? C9 C1 C2 C3 -173.45(15) . . . . ? C1 C2 C3 C4 0.7(3) . . . . ? C2 C3 C4 C5 -1.8(3) . . . . ? C3 C4 C5 C6 0.7(2) . . . . ? C2 C1 C6 C5 -2.5(2) . . . . ? C9 C1 C6 C5 173.16(14) . . . . ? C2 C1 C6 C7 178.46(14) . . . . ? C9 C1 C6 C7 -5.92(18) . . . . ? C4 C5 C6 C1 1.4(2) . . . . ? C4 C5 C6 C7 -179.73(16) . . . . ? C1 C6 C7 O1 170.49(16) . . . . ? C5 C6 C7 O1 -8.5(3) . . . . ? C1 C6 C7 C8 -9.11(17) . . . . ? C5 C6 C7 C8 171.91(15) . . . . ? C10 N1 C8 C15 74.06(17) . . . . ? C10 N1 C8 C7 -167.47(13) . . . . ? C10 N1 C8 C9 -53.96(19) . . . . ? O1 C7 C8 N1 -39.8(2) . . . . ? C6 C7 C8 N1 139.78(13) . . . . ? O1 C7 C8 C15 81.65(18) . . . . ? C6 C7 C8 C15 -98.73(14) . . . . ? O1 C7 C8 C9 -160.22(15) . . . . ? C6 C7 C8 C9 19.40(15) . . . . ? C2 C1 C9 O2 71.4(2) . . . . ? C6 C1 C9 O2 -103.84(14) . . . . ? C2 C1 C9 C8 -166.84(15) . . . . ? C6 C1 C9 C8 17.97(16) . . . . ? N1 C8 C9 O2 -17.83(17) . . . . ? C15 C8 C9 O2 -146.24(12) . . . . ? C7 C8 C9 O2 98.47(13) . . . . ? N1 C8 C9 C1 -138.06(12) . . . . ? C15 C8 C9 C1 93.53(13) . . . . ? C7 C8 C9 C1 -21.76(14) . . . . ? C11 O4 C10 O3 -9.8(2) . . . . ? C11 O4 C10 N1 171.69(12) . . . . ? C8 N1 C10 O3 164.37(15) . . . . ? C8 N1 C10 O4 -17.1(2) . . . . ? C10 O4 C11 C14 179.38(13) . . . . ? C10 O4 C11 C13 61.47(19) . . . . ? C10 O4 C11 C12 -63.16(18) . . . . ? N1 C8 C15 C20 -156.42(13) . . . . ? C7 C8 C15 C20 85.06(16) . . . . ? C9 C8 C15 C20 -27.39(18) . . . . ? N1 C8 C15 C16 24.26(18) . . . . ? C7 C8 C15 C16 -94.27(15) . . . . ? C9 C8 C15 C16 153.29(13) . . . . ? C20 C15 C16 C17 2.1(2) . . . . ? C8 C15 C16 C17 -178.53(14) . . . . ? C15 C16 C17 C18 -0.5(2) . . . . ? C16 C17 C18 C19 -1.1(2) . . . . ? C17 C18 C19 C20 1.1(2) . . . . ? C18 C19 C20 C15 0.6(2) . . . . ? C16 C15 C20 C19 -2.2(2) . . . . ? C8 C15 C20 C19 178.46(14) . . . . ? loop_ _geom_hbond_atom_site_label_D _geom_hbond_atom_site_label_H _geom_hbond_atom_site_label_A _geom_hbond_distance_DH _geom_hbond_distance_HA _geom_hbond_distance_DA _geom_hbond_angle_DHA _geom_hbond_site_symmetry_A O2 H2A O3 0.84 1.95 2.7897(16) 177.9 3_656 _diffrn_measured_fraction_theta_max 0.982 _diffrn_reflns_theta_full 68.23 _diffrn_measured_fraction_theta_full 0.982 _refine_diff_density_max 0.324 _refine_diff_density_min -0.318 _refine_diff_density_rms 0.035