Structures and energetics of clusters surrounding diatomic anions stabilized by hydrogen, halogen, and other noncovalent bonds

Abstract

Diatomic anions CN–, NO–, and OH– are surrounded by 2, 3, and 4 ligand molecules drawn from the HF, HCl, XF, YF2, ZF3, TF4, and TrF3 set wherein X = Cl, Br, Y = S, Se, Z = P, As, T = Si, Ge, and Tr = Al, Ga. In the case of two ligands, both interact with the N of NO– and the O of OH–, but one approaches either end of CN–. Unlike the H and halogen bonding units, as the number of ligands increases there is a tendency for chalcogen, pnicogen, tetrel, and triel-bonding ligands to form a cage around the central anion, with strong inter-ligand noncovalent bonds. There are a number of unusual features observed as well, including proton transfers from the ligands to the central anion, halogen atom sharing, linearization of normally highly bent YF2 molecules, F-sharing between tetrel atoms, and OH–⋯F H-bonds. Triel-bonding ligands engage in the strongest binding but the patterns of the other types of ligands depend upon the particular central anion and the number of ligands involved.