Activation and Desulfurization of Thiophene and Benzothiophene by Iron Carbonyls

The synthesis, reactivity, and structure of thiaferroles Fe//2(R//2C//4H//2S)(CO)//6 and benzothiaferroles Fe//2(C//8H//6S)(CO)//6(1) are surveyed. These compounds are prepared by the reaction of Fe//3(CO)//1//2 with thiophenes and benzothiophenes. The benzothiaferrole 1 undergoes oxidative demetalation to give the cyclic thioester thiocoumarin C//9H//6OS. Solutions of 1 are stable at 185 degree C under N//2; at 160 degree C, high pressures of CO convert 1 into Fe(CO)//5 and benzothiophene, i. e. reductive elimination. Solutions of 1 react with H//2 to give primarily ethylbenzene together with 2-ethylbenzenethiol and bis(2-ethylphenyl) sulfide.