Chemical bonding in the lightest tri-atomic clusters; H 3+, Li 3+ and B 3−

Abstract

Detailed topological charge density analysis and the Quantum Theory of Atoms in Molecules (QTAIM) calculations has been performed on equilibrium geometries of the three lightest tri-atomic clusters; H 3 +, Li 3 + and B 3 −. Characteristics of critical points of charge density, the effects of occupied molecular orbitals on topology of charge density, the stability of molecular graphs toward nuclear excursions and the QTAIM integration results were used to draw a picture of bonding in these clusters. Topological networks in H 3 + and B 3 − are unstable but molecular graph of Li 3 + is stable under finite geometry changes. H 3 + is best represented as a 3-membered ring; lithium atoms in Li 3 + surround the electrons in basin of a Non-Nuclear Maximum (NNM) by an electrostatic interaction; and in B 3 − an extended bonding pattern was found.