211516-45-9Relevant academic research and scientific papers
Activation of the carbon-sulfur bonds in benzothiophenes by precoordination of transition metals to the carbocyclic ring
Dullaghan, Conor A.,Zhang, Xiao,Greene, David L.,Carpenter, Gene B.,Sweigart, Dwight A.,Camiletti, Chiara,Rajaseelan, Edward
, p. 3316 - 3322 (1998)
Coordination of an electrophilic transition-metal fragment, MLn, to the carbocyclic ring of benzothiophene (BT) to form (η6-BT)MLnm+ activates a C-S bond to cleavage by the weak nucleophile Pt(PPh3)3, with concomitant insertion of Pt(PPh3)2. The rate of formation of the resulting metallathiacyclic insertion products, {(η6-BT·Pt(PPh3)2}ML nm+, depends on the metal fragment in the order MLn = Ru(C6Me6)2+, Mn(CO)3+ > FeCp+, RuCp+ ? Cr(CO)3, with no reaction occurring in the absence of a MLn activating group. All of the unsubstituted benzothiophene complexes undergo regiospecific cleavage of the olefinic C-S bond rather than the aryl C-S bond, which is likely a consequence of steric congestion that would exist if insertion had occurred at the latter site. The X-ray structures of the metallathiacycles {(η6-BT·Pt(PPh3)2}Mn(CO) 3+ and {(η6-BT·Pt(PPh3)2}FeCp+ are reported. The complexes (η5-2,5-dimethylthiophene)Mn(CO)3+ and (η6-dibenzothiophene)Mn(CO)3+ also undergo rapid C-S bond cleavage with metal insertion in the presence of Pt(PPh3)3. The results suggest that π-adsorption of a thiophenic substrate on a catalyst surface in hydrodesulfurization reactions is a viable way to facilitate C-S bond cleavage, as well as subsequent desulfurization and hydrogenolysis.
