A theoretical study on the stability difference of the borane BnHn2− and carborane C2Bn−2Hn(5 ≤ n ≤ 7) clusters

Abstract

In order to study the electronic structure and structural stability of borane and carborane C2Bn−2Hn (5 ≤ n ≤ 7) clusters, especially the stability difference between the borane and carborane C2B3H5. The frontier orbital energy levels of the borane and carborane C2Bn−2Hn (5 ≤ n ≤ 7) clusters are calculated at CCSD(T)/aug-cc-pVXZ//B3LYP/def2-TZVPP level. The results are further analyzed by qualitative frontier orbital method based on the cap–ring interaction. The results reveal that: (1) the larger Egap(HOMO-LUMO energy gap) of carborane C2Bn−2Hn (5 ≤ n ≤ 7) clusters than borane (5 ≤ n ≤ 7) clusters originates from the more effective cap–ring orbital overlap of carborane C2Bn−2Hn (5 ≤ n ≤ 7) clusters than that of borane (5 ≤ n ≤ 7) clusters; (2) the smallest Egap of the borane results from the highest energy level of the ring symmetry-adapted linear combination orbital of cluster; and (3) the largest Egap of the carborane C2B3H5 is induced by the most effective cap–ring orbital interaction of C2B3H5 cluster. © 2014 Wiley Periodicals, Inc.