An Ab Initio Investigation of the Geometries and Binding Strengths of Tetrel-, Pnictogen-, and Chalcogen-Bonded Complexes of CO₂, N₂O, and CS₂ with Simple Lewis Bases: Some Generalizations.

Ibon Alkorta,Anthony C Legon

doi:10.3390/molecules23092250

Abstract

Geometries, equilibrium dissociation energies (De), and intermolecular stretching, quadratic force constants (kσ) are presented for the complexes B⋯CO2, B⋯N2O, and B⋯CS2, where B is one of the following Lewis bases: CO, HCCH, H2S, HCN, H2O, PH3, and NH3. The geometries and force constants were calculated at the CCSD(T)/aug-cc-pVTZ level of theory, while generation of De employed the CCSD(T)/CBS complete basis-set extrapolation. The non-covalent, intermolecular bond in the B⋯CO2 complexes involves the interaction of the electrophilic region around the C atom of CO2 (as revealed by the molecular electrostatic surface potential (MESP) of CO2) with non-bonding or π-bonding electron pairs of B. The conclusions for the B⋯N2O series are similar, but with small geometrical distortions that can be rationalized in terms of secondary interactions. The B⋯CS2 series exhibits a different type of geometry that can be interpreted in terms of the interaction of the electrophilic region near one of the S atoms and centered on the C∞ axis of CS2 (as revealed by the MESP) with the n-pairs or π-pairs of B. The tetrel, pnictogen, and chalcogen bonds so established in B⋯CO2, B⋯N2O, and B⋯CS2, respectively, are rationalized in terms of some simple, electrostatically based rules previously enunciated for hydrogen- and halogen-bonded complexes, B⋯HX and B⋯XY. It is also shown that the dissociation energy De is directly proportional to the force constant kσ, with a constant of proportionality identical within experimental error to that found previously for many B⋯HX and B⋯XY complexes.

Highlights

Investigation, both experimentally and theoretically, of non-covalent interactions among molecules is a topic of rapidly increasing interest
We present the geometries and interaction strengths of complexes of the type B· · · CO2, B· · · CS2, and B· · · N2 O for the series of Lewis bases, B = CO, HCCH, H2 S, HCN, H2 O, PH3, and NH3, as calculated ab initio at the CCSD(T)/aug-cc-pVTZ level of theory
Given the definitions of hydrogen and halogen bonds in terms of the interaction of nucleophilic regions of Lewis bases B with electrophilic regions near the atoms H of HX and X of XY, the aim of the work presented here is to examine by means of ab initio calculations (1) whether the complexes

Summary

Introduction

Investigation, both experimentally and theoretically, of non-covalent interactions among molecules is a topic of rapidly increasing interest. Each provides an electrophilic site by means of which either tetrel, pnictogen, or chalcogen bonds, respectively, could be formed Both CO2 and CS2 are non-dipolar; the molecular electric quadrupole moment is the first non-zero term in the expansion of the electric charge distribution; this moment is of opposite sign in the two molecules [11,12]. Given the definitions of hydrogen and halogen bonds in terms of the interaction of nucleophilic regions of Lewis bases B with electrophilic regions near the atoms H of HX and X of XY, the aim of the work presented here is to examine by means of ab initio calculations (1) whether the complexes. Carbon disulfide calculated for the 0.002 e/bohr iso-surface at the MP2/6-311++G** level

Theoretical Methods

Geometries

Molecular

Conclusions was through abinitio initio