Note. Preparation of 11-(2′-dimethylaminoethyl)-1,4,7-trimethyl-1,4,7,11-tetra-azacyclotetradecane, and characterisation of its nickel(II), copper(II), and zinc(II) complexes

Abstract

The new 14-membered, pendant-arm macrocyclic ligand, 11-(2′-dimethylaminoethyl)-1,4,7-trimethyl-1,4,7,11-tetra-azacyclotetradecane (L²), and some of its complexes with Cu^II, Ni^II, and Zn^II(M) of general formula [M(L²)]X₂(X = ClO₄^– or NO₃^–) have been isolated. The five-co-ordinate complex [Cu(L²)][ClO₄]₂ undergoes reversible protonation of the pendant arm to give [Cu(HL²)][ClO₄]₃. The complex [Ni(L²)][ClO₄]₂ is also five-co-ordinate but attempted selective protonation leads to complete dissociation of (L²) from the Ni²⁺ ion. The ¹³C n.m.r. spectrum of [Zn(L²)][NO₃]₂ reveals the presence of two species in aqueous solution, one symmetric and the other asymmetric.