Photosensitive Tin Sulfur Dioxide Complexes with Unexpected Bonding Modes.

Infrared spectra of the matrix-isolated Sn(η -O S), Sn(η -OSO), Sn(η -O S)(η -OSO), Sn(η -O S) OSn (η -SO), and Sn(μ -O )SnS molecules were observed following laser-ablated Sn atom reactions with SO during condensation in solid argon. The assignments for the major vibrational modes were confirmed by appropriate S O and SO isotopic shifts and density functional vibrational frequency calculations (B3LYP and BPW91). Interestingly, the mononuclear complexes are interconvertible; that is, irradiation induces the isomerization of Sn(η -O S) and Sn(η -O S)(η -OSO) to Sn(η -OSO) and Sn(η -O S) , respectively, and vice versa on annealing. However, there is no evidence of isomerization reaction in between the binuclear molecules OSn (η -SO) and Sn(μ -O )SnS. Bonding in these products is discussed, and the electronic structure changes associated with different bonding types are revealed, which is crucial for the observed photochemical reactions.