Modulating of the pnicogen-bonding by a H•••π interaction: An ab initio study

An ab initio study of the cooperativity in XH2P center dot center dot center dot NCH center dot center dot center dot Z and XH2P center dot center dot center dot CNH center dot center dot center dot Z complexes (X= F, Cl, Br, CN, NC; Z= C2H2, C6H6) connected by pnicogen-bonding and H center dot center dot center dot pi interactions is carried out by means of MP2 computational method. A detailed analysis of the structures, interaction energies and bonding properties is performed on these systems. For each set of the complexes considered, a favorable cooperativity is observed, especially in X=F and CN complexes. However, for a given X or Z, the amount of cooperativity effects in XH2P center dot center dot center dot CNH center dot center dot center dot Z complexes are more important than XH2P center dot center dot center dot NCH center dot center dot center dot Z counterparts. Besides, the influence of a H center dot center dot center dot pi interaction on a P center dot center dot center dot N (C) bond is more pronounced than that of a P center dot center dot center dot N (C) bond on a H center dot center dot center dot pi bond. The quantum theory of atoms in molecules shows that ternary complexes have increased electron densities at their bond critical points relative to the corresponding binary systems. The results also indicate that the strength of the P center dot center dot center dot N(C) and H center dot center dot center dot pi interactions increases in the presence of the solvent. (C) 2017 Elsevier Inc. All rights reserved.