Variable valence non-oxido and oxido-vanadium systems: exploring their interconversion in solution, and biological activity

Abstract

There is a contemporary interest in vanadium chemistry, which stems from the broad range of relevance and application of vanadium in biological as well as industrial processes. Therefore, the development of new vanadium complexes with improved pharmacological activity is of current interest. In contrast to the well-known oxido-vanadium(IV)/(V) complexes, relatively few non-oxido VIV and VV complexes, the so-called “bare” complexes, have been isolated and structurally characterized. On the other hand, it is wellknown that, for an oxido and alkoxido vanadium system, the solid-state chemistry may be different from that in solution. In fact, in solution the complexes may undergo ligand exchange, in some cases also redox reactions and/or formation of dimer and oligomers; thus, the main species present in solution may differ from that of the parent solid. Over the past few years, we have been working in the field of vanadium chemistry incorporating several mono and dibasic ligand systems, and have successfully isolated several oxido-vanadium(V),1-4 oxido-vanadium(IV),5 mixed valence oxidovanadium(IV,V),3 and some rare stable nonoxido-vanadium(IV) complexes 4,6 and accessed their solution chemistry and biological activity. In this presentation I will focus on some of our recent interesting results.