[ML(n)]2+ doubly charged systems: modeling, bonding, life times and unimolecular reactivity

Doubly charged species in the gas phase have been an oddity for many years, but the possibility of generating and detecting them with the new available experimental techniques has faced the scientific community with challenging questions regarding their stability, bonding and reactivity. In this paper we analyze, mainly from a theoretical perspective, these questions for the particular subset of [ML(n)](2+) dications, where M is a metal and L an organic or inorganic ligand. Special attention is devoted to the challenges associated with their theoretical description, in particular as far as their bonding and their life times are concerned. A survey of their unimolecular reactivity is also presented as well as a discussion of the information available on dication affinities, and how they correlate with proton affinities or monocation affinities in general.