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Two new polyamine ligands, L1 and L2, incorporating pyridyl and aliphatic amine donor sites have been prepared and their reaction with copper(ii) yields the mono- and binuclear complexes [Cu(L1)](ClO4)2 (1) and [Cl2Cu(L2)CuCl(H2O)]ClO4 (2), respectively. The X-ray structure of 1 confirms that the five nitrogen donors of L1 are bound to the central copper ion to give a distorted square pyramidal coordination sphere. In 2, L2 acts as a bridging ligand with its N3-donor coordination domains separated by a m-xylylene spacer group. An unusual feature of this latter complex is that symmetrical L2 gives rise to non-equivalent coordination behaviour at the individual copper sites; while both sites display five-coordination with distorted square pyramidal arrangements, they differ in having N3Cl2- and N3ClO-donor atom sets, respectively. The electron paramagnetic resonance (EPR) spectra of both complexes are discussed. Variable temperature magnetic susceptibility data confirmed the absence of magnetic interactions in 1 while a weak antiferromagnetic interaction between copper(ii) centres occurs in 2.

Analysis of the crystal structures of a variety of transition metal complexes in which the ligands are hypodentate, thus providing pendent ammonio, amino, and/or hydroxy groups, has been conducted with the objective of defining the labile interactions of these pendent groups. In the case of pendent ammonio groups, not only do they appear to be good H-bond donors but they are frequently involved in contacts suggestive of hyperdenticity at N. For pendent amino and hydroxy groups, of particular interest in regard to their potential activity as nucleophiles, their H-bond acceptor ability frequently seems to be rather limited and it is unclear whether it can be related to either the nature or the charge on the bound metal cation.

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