Spectroscopic observation of photo-induced metastable linkage isomers of coinage metal (Cu, Ag, Au) sulfur dioxide complexes

Abstract

Coinage metal atom (Cu, Ag, Au) reactions with SO₂ were investigated by matrix isolation infrared absorption spectroscopy and density functional theory electronic structure calculations. Both mononuclear complexes M(η¹-SO₂) (M = Ag, Au) and M(η²-O₂S) (M = Ag, Cu) were observed during condensation in solid argon or neon. Interestingly, the silver containing mononuclear complexes are interconvertible; that is, visible light induces the isomerization of Ag(η¹-SO₂) to Ag(η²-O₂S) and vice versa on annealing. However, there is no evidence of similar interconvertibility for the Cu(η²-O₂S) and Au(η¹-SO₂) molecules. These different behaviors are discussed within the bonding considerations for all of the obtained products.