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

The rhodium dimer [Rh(dippe)(mu-H)](2) (1) reacts with dibenzothiophene to form the C-S cleavage product [Rh-2(dippe)(2)(mu-SC12H9)(mu-H)] (3). Complex I also reacts with 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene to form [Rh-2(dippe)(2)(mu-S-MeC(12)H8)(mu-H)] (4) and [Rh-2(dippe)(2)-(mu-S-Me2C12H7)(mu-H)] (6), respectively. Reaction with phenoxythiin forms [Rh-2(dippe)(2)(mu-S-C6H4-OC6H5)(p-H)] (8). In 3, rhodium addition to the ortho C-H bond of the beta-ring, of the biphenylthiolate substituent does not occur at 100 degrees C. The crystal structures of [Rh-2(dippe),(mu-Cl)(mu-H)] (2), 4, 6, and 8 indicate that each complex contains a nearly planar Rh-2(mu-X)(mu-H) core. The El NM R 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 di benzothiophene, while [Rh-2(dippe)(2)(mu-Cl)(mu-H)] cleaves a C-S bond of DBT to form [Rh-2(dippe)(2)(mu-Cl)(mu-SC12H9)] (9).