Chapter 8: Vanadium-oxide Molecular Catalysts in Non-aqueous Solution

In this chapter, various vanadium-oxide clusters are exhibited and their spontaneous formation in solution is rationalized. Unlike organic chemistry that is governed by the formation of covalent bonds, inorganic-oxide molecules are dynamic species due to their flexible ionic bonds and have an exquisite beauty showing a spectrum of beautiful colours arising from various coordination modes and valence states. In a catalytic reaction using a vanadate source, vanadium-oxide clusters are often formed and transformed – it is also easy to restore the structure back to the original form. The relative easiness of the transformation in a different structure of blocks, tubes, bowls, cages, spheres and rings is key to understanding each catalytic process. The analogy between the graphite structure and the V₂O₅ stacked-2D-sheet structure explains the formation of tubes and spheres and is reminiscent of the discovery of nano-tubes and fullerenes in carbon chemistry. Vanadium chemistry enjoys an easiness of modification and incorporation of a guest molecule that it can feasibly control compared to the stubborn fullerene host–guest complex.