Black body radiation induced hydrogen formation in hydrated vanadium cations V+(H2O)n

Hydrated vanadium cations V+(H2O)n, n = 5–30, are stored in the collision-free environment of an FT-ICR mass spectrometer and their reactions due to absorption of black body radiation are studied. Besides the loss of water ligands, the clusters show two different intracluster redox reactions, whose branching ratios are strongly size-dependent. Oxidation to the +II state results in V(OH)+(H2O)n ions, and a concurrent release of atomic hydrogen. Alternatively V(OH)2+(H2O)n clusters can form leaving vanadium in the +III state, common in aqueous solutions, and simultaneously molecular H2 evaporates from the cluster. This behavior reflects the properties of transition metals, and the ability of vanadium to form stable compounds in a variety of oxidation states, and differs from the previously studied intracluster reactions involving the hydrated monovalent main group metals Mg+ and Al+. These only react to their preferred oxidation states, MgOH+ and Al(OH)2+, respectively.