Quantum chemical calculations are performed to analyze the cooperative effects in cyclic (LiCN)3–8 and (HCN)3–8 clusters. Molecular geometries and interaction energies of the complexes are investigated using the B3LYP and MP2 methods employing 6-311++G** basis set. Our results strongly suggest that cooperative effects induced by lithium and hydrogen bonds are significant in cyclic (LiCN)3–8 and (HCN)3–8 clusters, respectively. The intermolecular distances observed in the cyclic (HCN)n exhibit a quite larger bond contractions than those found in the (LiCN)n. The results of electron density analysis suggest that the capacity of the cyclic LiCN and HCN clusters to concentrate electrons at the Li⋯N and H⋯N critical points, respectively, enhance considerably with cluster size. The results also indicate that the magnitude of cooperative effects is more important for cyclic HCN than for LiCN clusters.
