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Models for the Homogeneous Hydrodesulfurization of Benzothiophenes. Carbon−Sulfur Bond Cleavage, Hydrogenolysis, and Desulfurization Reactions Mediated by Coordination of the Carbocyclic Ring to Manganese and Ruthenium

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journal contribution
posted on 21.04.1998, 00:00 by Xiao Zhang, Conor A. Dullaghan, Eric J. Watson, Gene B. Carpenter, Dwight A. Sweigart
Chemical reduction of a series of (η6-benzothiophene)Mn(CO)3+ complexes (10ac) under CO affords neutral dimanganese metallathiacyclic complexes (12ac), which have a Mn(CO)4 moiety inserted into the C(aryl)−S bond. Reduction of (η6-benzothiophene)Ru(C6Me6)2+ in the presence of CO and (η6-1-Me-naphthalene)Mn(CO)3+ affords an analogous cationic bimetallic (15), which is converted to a neutral cyclohexadienyl complex (16) by hydride addition to the carbocyclic benzothiophene ring. The sulfur atom in the metallathiacyclic ring in 12 and 16 is nucleophilic and reacts with electrophiles CF3SO3Me, HBF4, and W(CO)5(THF) to afford complexes such as 6, 14, and 17. Treatment of 12 with H2 results in hydrogenolysis of the Mn−C σ bond and formation of the bimetallic Mn2(CO)8(H)(SCHCHPh) (8), which contains a Mn−Mn bond and bridging hydride and thiolate ligands. Reaction of 6 and 17 with H2 results in desulfurization of the benzothiophene and formation of a mixture of Mn(CO)5SR and [Mn(CO)4SR]2 (R = H, Me). Crystal structures are reported for 9 (R = Me), 12b, and 16.