Electronic structure, stability, and cooperativity of chalcogen bonding in sulfur dioxide and hydrated sulfur dioxide clusters: a DFT study and wave functional analysis

Natarajan Sathiyamoorthy Venkataramanan

doi:10.1007/s11224-021-01827-6

Abstract

Density functional theory calculations and wave functional analysis are used to examine the (SO2)n and (SO2)n–H2O clusters with n = 1–7. The nature of interactions is explored by molecular electrostatic potentials, electron density distribution, atoms in molecules, noncovalent interaction, and energy decomposition analysis. The putative global minimum of SO2 molecules has a 3D growth pattern with tetrahedral. In the hydrated SO2 clusters, the pure hydrogen bond isomers are less stable than the O–S chalcogen bond isomers. The cluster absorption energy of SO2 on water increases with the size of sulfur dioxide, implying reactivity of sulfur dioxide with water increases with size. The presence of cooperativity was evident from the excellent linearity plot of binding energy/polarizability vs the number of SO2 molecules. Molecular electrostatic potential analysis elucidates the reason for the facile formation of S–O chalcogen than hydrogen bonding in hydrated sulfur dioxide. Atoms in molecule analysis characterize the bonds chalcogen and H bonds to be weak and electrostatic dominant. EDA analysis shows electrostatic interaction is dominated in complexes with more intermolecular chalcogen bonding and orbital interaction for systems with intermolecular H-bonding. The reduced density gradient (RDG) analysis of sulfur dioxide clusters has blue patches and green patches due to S–O chalcogen bonding O–O electrostatic interaction. The RDG analysis of hydrated sulfur dioxide clusters shows intensive blue patches and green patches for the existence of S–O chalcogen and hydrogen bonding respectively. Thus, the presence of strong electrostatic S–O chalcogen interaction and weak H bonds acts cooperatively and stabilize the hydrated sulfur dioxide clusters.

Highlights

Sulfur dioxide (SO2) is a primary gas molecule responsible for air pollutions
The pristine SO2 and binary intermolecular clusters formed by SO2 molecules and water was investigated using density functional theory and wave functional methods
In the hydrated SO2 clusters, the structures with chalcogen bonding alone or with only hydrogen bonding are less stable than structures with both bonding

Summary

Introduction

Sulfur dioxide (SO2) is a primary gas molecule responsible for air pollutions. Its source of accumulation in the earth’s atmosphere is being both anthropogenic and natural including volcanic eruptions [1,2]. Because of its prominence in atmospheric implication, the interaction between water and sulfur dioxide has been the subject of many experimental and theoretical studies [4,5,6]. To understand the atmospheric implication of SO2, the interaction of SO2 with water molecules was studied in gas or aqueous aerosols by both experimental and theoretical methods. The interaction of sulfur dioxide clusters with water molecules is not known to the best of our knowledge. The nature of interaction and stability of the cluster are addressed using energetic analysis, molecular electrostatic potential (MEP), electron density difference (EDD), noncovalent interaction–reduced density gradient (NCI-RDG) analysis, and atoms in molecule (AIM) analysis. The cooperativity effect and the role of hydrogen bonding in (SO2)n–H2O clusters in cooperativity are investigated in terms of geometry, pair-wise interaction energy, MEP and AIM analysis. Energy Decomposition Analysis (EDA) was carried out for (SO2)n–H2O clusters to provide insight into the role of driving forces for the hydration of sulfur dioxide clusters

Computational Details

Results And Discussions

Nature of Intermolecular Interaction

Atoms in molecules

EDA analysis

Non-covalent interactions-Reduced density gradient analysis

Conclusion