Supporting conformational change at metal centres. Part 2: four and five coordinate geometry

The X-ray crystal structures of pyridino-(N,N'-bis(salicylidene)-1,2-ethylenediamine)zinc, bis-(N,N'-bis(salicylidene)-1,3-propanediamine zinc) and bis-((mu-acetato-O,O')-(N,N'-bis(salicylidene)-1,4-butanediamine) zinc) zinc are reported. These elusive motifs complete a structure based matrix of compounds for the late transition metals zinc with the popular ligands N,N'-bis(salicylidene)1,2-ethylenediamine, NN'-bis(salicylidene)-1,3-propanediamine and N,N'-bis(salicylidene)-1,4-butanediamine. Coupled with the structural data from previously reported zinc complexes, it is possible to provide an in depth analysis of the behaviour of these three ligand systems within a five coordinate environment. The information is further combined with structural data on the homologous copper and nickel complexs to provide an overview of the conformational flexibility of these three ligands within a four, five or six coordinate environment. It is demonstrated that the more neglected N,N'-bis(salicylidene)-1,4-butanediamine motif may have great potential for supporting chemistry at a metal centre where significant changes in coordination number and geometry are desired. (C) 2002 Elsevier Science Ltd. All rights reserved.