Copper(II) and nickel(II) complexes of N,N′,N″,Nâ�—-tetrakis(2-aminoethyl)-1,4,7,11-tetra-azacyclotetradecane (taei), -1,4,8,12-tetra-azacyclopentadecane (taep), and -1,5,9,13-tetra-azacyclohexadecane (taeh). Crystal structures of [Cu2(taep)][ClO4]4, [Cu2(taeh)][ClO4]4, and [Cu2(N3)(taeh)][ClO4]3
Abstract
New octaamine dinucleating ligands, N,N′,N″,N‴-tetrakis(2-aminoethyl)-1,4,7,11-tetra-azacyclo-tetradecane (taei), -1,4,8,12-tetra-azacyclopentadecane (taep), and -1,5,9,13-tetra-azacyclohexadecane (taeh) and their complexes with CuII and NiII were synthesized. Of the 19 complexes isolated, the structures of [Cu2(taep)][ClO4]4, [Cu2(taeh)][ClO4]4, and [Cu2(N3)(taeh)][ClO4]3 were determined by X-ray crystal analysis. In all these complexes each copper is co-ordinated by two ring nitrogens and two pendant amino nitrogens, and the two CuN4 co-ordination sets face each other. In the azido complex the N3– is bonded to both coppers in an end-to-end fashion. The dinuclear complexes [Cu2L][ClO4]4(L = taei or taep) further incorporate various anions between the two coppers to form [Cu2X(L)][ClO4]3. However, only the azido complex was obtained with taeh. The results are discussed in terms of the ring-size effect.