Thermochemical properties, electronic structure and bonding of mixed lithium boron clusters (BnLi, n=1-8) and their anions

The electronic structure and molecular properties of a series of small mixed lithium boron clusters BnLi (n = 1-8) in both neutral and anionic states are investigated using quantum chemical methods. The lowest-energy structures are identified. Standard heats of formation, adiabatic electron affinities (EAs) and vertical detachment energies (VDEs) are predicted using coupled-cluster theory CCSD(T)/6-311+G(d) calculations. Addition of Li to B-n to form BnLi clusters marginally distorts the geometries of the parent B-n. The chemical bond in BnLi has a highly ionic character in which the positive charges are located on Li. MO analysis confirms a similar degree of aromaticity between BnLi and B-n(-). The relative stabilities of the clusters are evaluated using the average binding energy (E-b), second order difference in energy (Delta E-2), resonance energy (RE) and normalized resonance energy (NRE). Both REs and NREs quantities of the Li-doped boron clusters are consistently larger than those of the pure Bn clusters. The B3Li species exhibits a remarkably high stability within the BnLi series. (C) 2010 Elsevier B.V. All rights reserved.