Carbon−Sulfur Bond Activation of Dibenzothiophenes and Phenoxythiin by [Rh(dippe)(μ-H)]2 and [Rh2(dippe)2(μ-Cl)(μ-H)

Abstract

The rhodium dimer [Rh(dippe)(μ-H)]2 (1) reacts with dibenzothiophene to form the C−S cleavage product [Rh2(dippe)2(μ-SC12H9)(μ-H)] (3). Complex 1 also reacts with 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene to form [Rh2(dippe)2(μ-S-MeC12H8)(μ-H)] (4) and [Rh2(dippe)2(μ-S-Me2C12H7)(μ-H)] (6), respectively. Reaction with phenoxythiin forms [Rh2(dippe)2(μ-S-C6H4OC6H5)(μ-H)] (8). In 3, rhodium addition to the ortho C−H bond of the β-ring of the biphenylthiolate substituent does not occur at 100 °C. The crystal structures of [Rh2(dippe)2(μ-Cl)(μ-H)] (2), 4, 6, and 8 indicate that each complex contains a nearly planar Rh2(μ-X)(μ-H) core. The 1H NMR spectra of 3, 4, and 6 suggest that the pyramidal geometry at the sulfur atom is maintained in solution and that sulfur inversion is absent. Unreacted 1 catalyzes H/D exchange between C6D6 and the biphenylate substituent of 3 faster than it cleaves the remaining C−S bond to make free biphenyl. Complex 3 is unreactive toward excess dibenzothiophene, whil...