Reactions of 2-benzo[b]thienyl (2-BTyl) complexes with acid to give Cp(PMe[sub 3])[sub 2]Ru([eta][sup 1](S)-BT)[sup +] and Cp(CO)(PPh[sub 3])Ru([eta][sup 1](S)-BT[sup +]): A model for benzo[b]thiophene (BT) deuterium exchange on hydrodesulfurization catalysis

Hydrodesulfurization (HDS) of benzo[b]thiophene (BT) over Co-Mo/Al[sub 2]O[sub 3] catalysts to give ethylbenzene and H[sub 2]S is proposed to occur by two mechanistic pathways either by initial hydrogenation to give 2,3-dihydrobenzothiophene followed by desulfurization to form the final products or by initial desulfurization to give vinylbenzene followed by hydrogenation to ethylbenzene. Regardless of the pathway, the reaction involves only the thiophenic part of BT as the benzene ring is not hydrogenated. Also, deuterium exchange of BT, when passed with D[sub 2] over HDS catalysts, occurs predominantly in the 2- and 3-positions of the thiophene rather than in the benzene ring. A mechanism which accounts for this deuterium exchange has been proposed by Cowley. In order to probe the possibility that [sigma]-coordination of 2-benzothienyl (2-BTyl) to a metal accounts for deuterium exchange at the 2-position as proposed by Cowley, the authors describe herein the synthesis of 2-BTyl complexes of Ru and examine their reactions with CF[sub 3]SO[sub 3]H. 19 refs., 2 figs.