Complexation of hydrogen by lithium: structures, energies and vibrational spectra of Li⁺(H₂)n(n= 1–4), Li-H(H₂)mand Li-H⁺(H₂)m(m= 1–3)

The interaction of metals with hydrogen is of importance in several areas of technology. Lithium-hydrogen complexes are particularly amenable to theoretical study. Although no stable compound of the Li atom and H2 has been found, a weak dative interaction forms between the σ bond of H2 and the positively charged Li atom for Li+, Li-H+, and Li-H. At least four H2 molecules can be complexed by Li+, and three by Li-H+ and Li-H. The presence of the Li ion does not substantially weaken the H2 bond, nor is the energy of dissociation affected; however, the Li ion does form stable complexes with the dissociated H atoms.