A Bridge Too Far: Testing the Limits of Polypyridyl Ligands in Bridging Soluble Subunits of a Coordination Polymer

Starting with a coordination polymer, {[Cu(L)]2}n (1 where H2L = salicylidene-2-aminophenol), we have explored the ability of polypyridyl ligands (P) to bridge the monomer complex to form nine {[Cu(L)]2(P)} complexes. The identity and solution stability of the [Cu(L)] units has been investigated through a novel combined UV-vis/EPR experiment and it has been found to be a stable supramolecular building unit for the construction of discrete complexes and coordination polymers. The reorganization of [Cu(L)] units to a new coordination polymer on addition of 4, 4′- bipyridine markedly changes the connectivity of the structure and the magnitude of the antiferromagnetic interactions through reorientation of the Cu(II) orbitals. We also present the structure of 1, 80 years after its synthesis was first reported.