Theoretical study of one‐electron bonds in a series of high‐spin lithium–beryllium–hydrogen clusters: “Valence shell single‐electron repulsion” rule and electron localization function analysis

Abstract

AbstractA series of high‐spin clusters containing Li, H, and Be in which the valence shell molecular orbitals (MOs) are occupied by a single electron has been characterized using ab initio and density functional theory (DFT) calculations. A first type (5Li2, n+1LiHn+ (n = 2–5), 8Li2H) possesses only one electron pair in the lowest MO, with bond energies of ∼3 kcal/mol. In a second type, all the MOs are singly occupied, which results in highly excited species that nevertheless constitute a marked minimum on their potential energy surface (PES). Thus, it is possible to design a larger panel of structures (8LiBe, 7Li2, 8Li, 4LiH+, 6BeH, n+3LiH (n = 3, 4), n+2LiH (n = 4–6), 8Li2H, 9Li2H, 22Li3Be3 and 22Li6H), single‐electron equivalent to doublet “classical” molecules ranging from CO to C6H6. The geometrical structure is studied in relation to the valence shell single‐electron repulsion (VSEPR) theory and the electron localization function (ELF) is analyzed, revealing a striking similarity with the corresponding structure having paired electrons. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007