(THIOALLYL)IRON TRICARBONYL COMPLEXES

The tetramethylallene episulfide 1a reacts with Fe2(CO)9 to afford (tetramethylthioallyl)iron tricarbonyl complex 2a and (mu-2,4-dimethyl-2-pentene-3,4-dithiolato-kappa(2)S:kappa(2)S')diiron hexacarbonyl (3). The structure of 3 was characterized crystallographically. The reaction of 1-tert-butyl-3,3-diphenylallene 1-episulfide (1b) with Fe2(CO)9 resulted in the formation of (1-tert-butyl-3,3-diphenyl-2-thioallyl)iron tricarbonyl (2b). The (thioallyl)iron tricarbonyl complex 2b exists as an eta(4)-pi-complex as revealed by H-1 and C-13 NMR spectroscopy as well as by X-ray diffraction analysis. Thermolysis of 2b in the presence of carbon monoxide gave 2-tert-butyl-4-(diphenylmethylidene)thietan-3-one (7). Complex 2b reacts with PPh3 to give 7 and metalathiopentanone 8. Heating of 8 gave 7 and a corresponding allene 5b. According to the structure of 7 and 8 and chemical observations, thermolysis of 8 took place to give 7 via a metathesis-like reaction of 1,2- or 1,3-metalathietane 13 and 15.