LZnX complexes of tripodal ligands with intramolecular RN-H hydrogen bonding groups: structural implications of a hydrogen bonding cavity, and of X/R in the hydrogen bonding geometry/strength.

摘要: Tripodal ligands N(CH2Py)3-n(CH2Py-6-NHR)n(R=H, n=1-3 L1-3, n=0 tpa; R=CH2tBu, L'1-3) are used to investigate the effect of different hydrogen bonding microenvironments on structural features their LZnX complexes (X=Cl-, NO3-, OH-). The X-ray structures [(L2)Zn(Cl)](BPh4)2.0.5(H2O.CH3CN), [(L3)Zn(Cl)](BPh4)3.CH3CN, [(L'1)Zn(Cl)](BPh4) 1', [(L'2)Zn(Cl)](BPh4)2'.CH3OH, and [(L'3)Zn(Cl)](BPh4)3' have been determined exhibit trigonal bipyramidal geometries with intramolecular (internal) N-HCl-Zn bonds. structure [(L'2)Zn(ONO2)]NO3 4'.H2O two internal N-HO-Zn bonds has also determined. axial Zn-Cl distance lengthens from 2.275 A in [(tpa)Zn(Cl)](BPh4) 2.280-2.347 1-3, 1'-3'. Notably, average Zn-N(py) is progressively lengthened 2.069 2.159 2.182 triply cavity 3 3', respectively. Lengthening accompanied by a progressive shortening trans Zn-N bond 2.271 2.115 (2.113 3'). As result microenvironment distances at upper end range observed for bonds, whereas one shortest among N4 that induce geometry. Despite rigidity these tripodal ligands, geometry RN-HX-Zn OH-, NO3-) strongly dependent nature X, however, average, similar R=H, CH2tBu.