Effect of microhydration on the atmospherically important metastable carbonyl sulfide anion: Structure, energetic, and infrared study

Abstract

Structure, energetics, and vibrational frequency of the microhydrated carbonyl sulfide anion [OCS−(H2O)n (n = 1–6)] have been explored by the systematic ab initio study to have a comprehensive understanding about the hydration‐induced stabilization phenomenon of OCS−. Water binds with the OCS− in single hydrogen‐bonded (SHB) or double hydrogen‐bonded (DHB) fashion with OH S and OH O contacts. Maximum five water molecules can stay in a cyclic water network of these hydrated clusters forming interwater hydrogen bonding (IHB) with each other and out of this, maximum of two water molecules can bind directly to the OCS− in (DHB) arrangement. The stabilization energy values of OCS−(H2O)n depict that ion–water interaction is significant up to four water molecules and beyond that OCS− is stabilized by IHB between the water molecules. The CO stretching frequency of OCS− gets red shifted, whereas CS stretching frequency gets blue shifted on hydration. Charge analysis of hydrated clusters of OCS− indicates that negative charge moves toward oxygen from sulfur on hydration. © 2015 Wiley Periodicals, Inc.