Binding energies of LiH2 and LiH2+ and the ionization potential of LiH2

Abstract

The existence of the stable molecule LiH2 was proved experimentally for the first time by mass spectrometric measurements over dilute solutions of hydrogen in liquid lithium. From the measurements of the gaseous equilibria Li(g)+LiH2(g) =2 LiH(g), and LiH2(g)+Li2(g) =LiH(g)+Li2H(g), an atomization energy D°0(LiH2) =127.0±7 kcal/mole was obtained. The ionization potential of LiH2(g) was determined as I.P. (LiH2) =6.14±0.2 eV, from which the binding energy of the ion LiH+2, D°0 (LiH+2) =109.0±8 kcal/mole was deduced. The heat of formation was determined as ΔH°0 (LiH2) =14.75±7.0 kcal/mole. The results from this study were compared with those predicted using diatomic-in-molecules and valence only electronic structure theories.