Understanding microsolvation of Li+: structural and energetical analyses

Abstract

A stochastic exploration of the quantum conformational space for the (H₂O)_nLi⁺, n = 3, 4, 5 complexes produced 32 molecular clusters at the B3LYP/6–311++G** and MP2/6–311++G** levels. The first solvation shell is predicted to comprise a maximum of 4 water molecules. Energy decomposition analyses were performed to determine the relationship between the geometrical features of the complexes and the types of interactions responsible for their stabilization. Our findings reveal that electrostatic interactions are major players determining the structures and relative stabilities of the clusters. The formal charge on the Li atom leads to two distinct types of hydrogen bonds, scattered in a wide range of distances (1.61–2.32 Å), in many cases affording H-bonds that are considerably larger and considerably shorter than those in pure water clusters (typically ∼1.97 Å).