Microsolvation of metal ions: on the stability of [Zr(CH 3CN)] 4+ and other multiply charged ions

Abstract

The stability of highly charged gas phase metal ion solvates [M(Sol) n ] z+ ( z>2) is discussed based on a simple electrostatic model and density functional theory computations. It is often assumed that the observation of such ions will be increasingly difficult as z increases because they will be less and less stable, i.e., that they will have an increasing tendency to undergo spontaneous charge-separating dissociation into fragment ions of lower charge. It is shown here that for carefully chosen metal ions such as Zr 4+, this need not be the case—many highly charged metal solvates, such as [Zr(CH 3CN)] 4+, should exist with very significant metastable lifetimes. However, it may be difficult to isolate and identify such ions experimentally without the interference of competing processes such as charge-separating dissociation or charge reduction through electron transfer during collisions with other molecules in the ion source.