RgnBe3B3+: theoretical investigation of Be3B3+ and its rare gas capability.

A series of Be3B3+ and its rare gas (Rg) containing complexes RgnBe3B3+ (Rg = He-Rn, n = 1-6) have been predicted theoretically using the B3LYP, MP2, and CCSD(T) methods to explore structures, stability, charge distributions, and nature of bonding. Both Be3B3+ and RgBe3B3+ are the global minima on the potential energy surfaces. In the RgnBe3B3+ complexes, the dissociation energy drops with the increase in number of Rg. Natural bond orbital (NBO) and topological analysis of the electron density (AIM) show that the Rg-Be bonds for Kr-Rn have some covalent character. The Rg-Be bond is stabilized dominantly by the Rg → Be3B3+ σ-donation from the valence p orbital of Rg to the vacant valence LUMO orbital of Rgn-1Be3B3+. Besides, other two π-donations also play important roles in stabilizing the Rg-Be bonds.