MODELS FOR REACTION OF FERROCENE-1,1'-DITHIOL WITH DIOLEFINS - REACTIONS OF FERROCENETHIOLS WITH NORBORNADIENE AND NORBORNENE

Ferrocenethiol and ferrocene-1,1'-dithiol, Fe(C5H5)(C5H4SH) and Fe(C5H4SH)2 respectively, can be added to both norbornadiene and norbornene in a radical-induced process. The reaction of ferrocenethiol with norbornadiene (1:10) in toluene at 70-degrees-C gives a mixture of 1:1 addition products containing 3-ferrocenylthio-nortricyclane (I) as the main component (ca. 80%); side-products are the substituted norbornene derivatives 5-exo- and 5-endo-ferrocenylthio-norborn-2-ene (II and III) as well as 7-anti-ferrocenylthio-norborn-2-ene (IV). Only traces of addition compounds containing ferrocenethiol and norbornadiene in a 2:1 ratio were obtained and identified by mass spectrometry. The radical-initiated addition of ferrocenethiol to norbornene leads, even with an excess of norbornene, to the preferential formation of diferrocenyldisulfide in addition to 2-exo- and 2-endo-ferrocenylthio-norbornane (V and VI). In an analogous manner, di[1'-(2-exo-norbornylthio)ferrocenyl]disulfide (VII) is obtained from the reaction of ferrocene-1,1'-dithiol with excess norbornene. The new ferrocene-sulphur compounds I-VII were characterized by their H-1 and C-13 NMR spectra.