C-S bond cleavages of thiophenes, benzothiophenes, and dibenzothiophenes

One of the common methods for the C-S bond cleavage of thiophene is the oxidative addition to low-valent coordinatively unsaturated complexes. However, one may encounter the concomitant cleavage of the C-H bond by the metal complexes. The development of preferential cleavage of the C-S bond over the competitive C-H bond is a topic of this reaction. 

Similar parallel reactions with benzothiophene are also observed in thermal 

Similarly, [RuCp(j7 -thiophene)]+[PF6] reacts with a variety of nucleophiles such as H , OMe , SMe and CH(C02Me)2 to cleave the C-S bond giving neutral complexes [114]. 

Activation of Substrates with Polar Single Bonds 

Transition metal complexes usually favor insertion into the carbon-sulfur bond adjacent to C(alkenyl)-S bond (type a), but some complexes insert into the C(aryl)-S bond (type b) [117]. Ab initio calculations suggest that the most important controlling factor for determining selectivity in the C-S bond cleavage of benzothiophene is the thermodynamic stability of the resulting metal-carbon bond [118], 

---