Modeling aspects of hydrodesulfurization by molybdenum hydride compounds: Desulfurization of thiophene and benzothiophene and C–S bond cleavage of dibenzothiophene

The molybdenum hydride complexes Mo(PMe3)5H2 and Mo(PMe3)4H4 are capable of cleaving the C–S bonds of thiophene, benzothiophene and dibenzothiophene. For example, Mo(PMe3)5H2 reacts with thiophene to give the η5-thiophene and butadiene–thiolate complexes, (η5-C4H4S)Mo(PMe3)3 and (η5-C4H5S)Mo(PMe3)2(η2-CH2PMe2). These complexes are also obtained from the reaction between Mo(PMe3)4H4 and thiophene under photochemical conditions, whereas at elevated temperatures thiophene is desulfurized to liberate but-1-ene. Similarly, Mo(PMe3)4H4 desulfurizes benzothiophene at elevated temperatures to liberate ethylbenzene, while the arylthiolate complex Mo(PMe3)4(SC6H4Et)H3 is obtained photochemically. Furthermore, Mo(PMe3)4H4 cleaves the C–S bond of dibenzothiophene to give [η6,κ1-C6H5C6H4S]Mo(PMe3)2H.