Molecules mimicking atoms: monomers and dimers of alkali metal solvated electron precursors

Phys Chem Chem Phys. 2018 Oct 7;20(37):24186-24191. doi: 10.1039/c8cp05497e. Epub 2018 Sep 13.

Abstract

Tetra-amino lithium and sodium complexes M(NH3) (M = Li, Na) have one or two electrons that occupy diffuse orbitals distributed chiefly outside the M(NH3) core. The lowest-energy 1s, 1p, and 1d orbitals follow Aufbau principles found earlier for beryllium tetra-ammonia complexes. Two ground state M(NH3)4 complexes can bind covalently by coupling their 1s1 electrons into a σ-type molecular orbital. The lowest excited states of the [M(NH3)4]2 species are obtained by promoting one or two electrons from this σ to other bonding or anti-bonding σ and π-type molecular orbitals. The electronic structure of solvated electron precursors provides insights into chemical bonding between super-atomic species that are present in concentrated alkali-metal-ammonia solutions.