Weak interaction between HCHY (Y=O, S) and LiCl: a theoretical study

Abstract

Ab initio calculations at second-order Moeller-Plesset (MP2) level with 6-31++G(d,p) basis set have been done on the intermolecular complexes of HCHY (Y=O, S) with LiCl. Ten possible orientations have been considered in each case and first a SCF optimization of geometry has been carried out. This was followed by a MP2 optimization starting from the SCF optimized geometry. Binding energies have been corrected for basis set superposition error and harmonic vibrational frequencies of the structures have been calculated to obtain the stable forms of the complexes. The most stable form is found to have a secondary hydrogen-bonding interaction in addition to the strong lithium-bonding interaction. The comparison of the strength of the interactions and structural parameters of the stable structures of HCHO···LiCl with HCHS···LiCl suggests that the lithium-bonding interaction with sulfur is weaker than that with oxygen.