CH•••π and π•••π interaction in benzene-acetylene clusters

Ab initio calculations at the MP2/aug-cc-pVXZ (where, X = D, T and Q) and CCSD(T)/aug-cc-pVDZ levels of theory and certain density functional theoretic calculations were carried out for different configurations of benzene-acetylene clusters. The interaction energy was estimated at the CCSD(T)/CBS limit. For the 1:1 complex, the T-shaped geometry (C-6v symmetry) was found to be the most stable (-2.72 kcal/mol) and the pi center dot center dot center dot pi stacked structure was the least stable (-0.58 kcal/mol). For the 1:2 complex, the ring-shaped (-5.87 kcal/mol) and the double T-shaped (-5.23 kcal/mol) geometries were found to be the most stable and the second most stable, respectively. (C) 2012 Elsevier B.V. All rights reserved.