Synthesis,Structure and Hydrolytic Properties of a Family of New Zn Complexes Containing Hexaazamacrocyclic Ligands

摘要

The synthesis,structure and spectrosopic properties of a family of Zn complexes containing a dinucleating hexaazamacrocyclic ligand (L) and anionic ligands (X) of general formula [Zn_2(X)_(4-n)(L)]~(n+) (1-8,L=H2p,H3p,Me2p,Me2p,Me2m,Me3pMe3m;X=Cl,n=0;X=NO_3,n=2) have been investigated.The solid-state structural characterisation has been performed by means of X-ray diffraction analysis for complexes 3,5,7.1/3CH_2Cl_2 and 8.The Zn complexes 5,7.1/3CH_2Cl_2 and 8 containing chloride ligands present a distorted N_2Cl_2 tetrahedral coordination with two non-coordinated N atoms of the macrocyclic ligand.On the other hand,complex 3,which contains nitriate ligands,displays an N_3O_2 pentacoordination with all the N atoms of the macrocyclic ligand bonded to the metal centrs.The different factors governing the relative Zn-Zn dispersition are discussed.NMR spectroscopy in solution reveals the presence of fluxional behaviour and a completely different structural arrangement than in the solid state.In particular,evidence for the formation and breaking of Zn-N bonds involving all the macrocyclic ligand atomic N atoms is obtained for the chloride complexes 2 and 4-8.Finally,complexes 1,3,5 and 7 hydrolyse p-nitrophenyl acetate (NA) with second-order rate constands ranging from 0.045 to 0.193 M~(-1)s~(-1),thus manifesting the influence of the ligands over the hydrolytic activity.