Evaluation of energies of isomeric SO2 complexes

Abstract

SO₂ binds to MHCl(CO)L₂ (M = Ru, Os; L = PⁱPr₃) to give a product in which SO₂ binds trans to hydride, and with an η¹-SO₂ binding mode, planar around sulfur, as shown in part by an X-ray diffraction study for M = Ru. We have investigated the structures and energies of various isomers and insertion (of SO₂ into the Ru–H bond) products of the observed product to evaluate, in a fixed molecular environment, their stabilities relative to the observed product, in which SO₂ functions as a Lewis base. In contrast to CH₂ insertion into the analogous Os–H bond, insertion of SO₂ into Ru–H here is not strongly favored. A search of the potential energy surface shows that η¹-SO₂ with pyramidal sulfur is not a stationary state.