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(η(1)-SO2) (M = Ag, Au) and M(η(2)-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(η(1)-SO2) to Ag(η(2)-O2S) and vice versa on annealing. However, there is no evidence of similar interconvertibility for the Cu(η(2)-O2S) and Au(η(1)-SO2) molecules. These different behaviors are discussed within the bonding considerations for all of the obtained products.