Structure and stability of B 5 C and C 5 B clusters

Geometry optimizations and vibrational frequencies of B 5 C and C 5 B clusters were calculated with the Becke‐3LYP method using the 6‐311+G(d) basis set and some stable configurations of B 5 C and C 5 B clusters have been found. The most stable structure of B 5 C is a planar six‐membered ring. However, for C 5 B clusters, the most stable structure is linear with a boron atom in position 3. Various configurations of B 5 C clusters containing three‐membered boron rings have predominance in energy, whereas various configurations of C 5 B clusters containing three‐membered carbon rings are disadvantageous in energy. In B 5 C clusters, isomer2 can be converted into isomer1 by surmounting an energy barrier of 43.83 kJ.mol −1 . In C 5 B clusters, the conversions of isomer5 into isomer2 and isomer7 into isomer2 have energy barriers of 19.66 and 20.57 kJ.mol −1 , respectively. Copyright © 2008 John Wiley & Sons, Ltd.