SYNTHESIS AND PROPERTIES OF NOVEL METAL CARBOXYLATES
Since the discovery of the quadruple bond by Cotton in the 1960s, the study of transition metal complexes containing metal-metal bonds has been extensive. A large sub-class of these compounds is the so-called "paddle-wheel" complexes that are ubiquitous in the transition series, with the tetracarboxylates, "M (μ-O CR) ", being the most abundant. Our focus has been on the mixed-valent diruthenium analogues, [Ru (μ-O CR) L ] (L = Lewis base, R = alkyl or aryl group), for two reasons: a) they are the only such type of complex with a "stable" mixed-valent (formally valent-average) state under normal conditions and b) they have a high magnetic moment (3 unpaired electrons) due to an accidental near-degeneracy of the π* δ* HOMO leading to a σ π δ (π*δ*) electronic configuration. This, along with their ability for facile exchange of their carboxylate bridges and axial ligands and along with a newly exploited "dimer disassembly" process, has allowed us to prepare a variety of derivatives with interesting electronic/magnetic, mesogenic and cytotoxic properties. What follows is a summary of work recently completed and currently in progress that can be divided into four projects, all dealing with some aspect of the coordination chemistry of [Ru (μ-O CR) L ] , (Ru (II,III)).
