Structures and infrared spectra of fluoride–hydrogen sulfide clusters from ab initio calculations: F−-(H2S)n, n = 1–5

Abstract

Clusters formed between a fluoride anion and several hydrogen sulfide molecules have been investigated via ab initio calculations at the MP2 level of theory, using Dunning’s augmented correlation consistent basis sets. Optimised geometries, vibrational frequencies, and enthalpy changes for the ligand association reactions are presented for clusters with up to five H₂S ligands interacting with a F⁻ anion. The minimum energy structure for the 1 : 1 F⁻-H₂S complex features proton transfer from the H₂S to the F⁻ anion, forming a planar C_s symmetry FH⋯SH⁻ structure. For the F⁻–(H₂S)₂ cluster, the FH⋯SH⁻ core remains and is solvated by a perturbed H₂S ligand. For the larger F⁻–(H₂S)_3–5 clusters, in addition to the FH⋯SH⁻–(H₂S)_n cluster forms, other minima featuring a ‘solvated F⁻’ anion are predicted. Calculated infrared spectra for the minima of each cluster size are presented to aid in assigning spectra from future experimental studies.