Fumarodinitrile: A versatile reagent in phosphaalkene and arsaalkene chemistry

Weber L, Kleinebekel S, Pumpenmeier L, Stammler H-G, Neumann B. Fumarodinitrile: A versatile reagent in phosphaalkene and arsaalkene chemistry. Organometallics. 2002;21(9):1998-2005.Reaction of equimolar amounts of the ferriophosphaalkene Cp*(CO)(2)FeP=C(Ph)NMe2 (1a) and fumarodinitrile in diethyl ether afforded the ferriophosphetane CP*(CO)(2)FeP-CH(CN)-CH(CN)-C(Ph)NMe2 (2a). Analogously, Cp*(CO)(2)FeP=C(tBu)NMe2 (1b) was converted into Cp*(CO)(2)FeP-CH(CN)-CH(CN)-C(tBu)NMe2 (2b). Evidence for the cyclic structure of 2a,b in the crystal was provided by the X-ray structural analysis of 2a. Whereas the phosphetane ring of 2b is retained in solution, product 2a in CH2Cl2 solution underwent an isomerization to give the acyclic secondary ferriophosphane Cp*(CO)(2)Fe-P(H)-CH(CN)-C(CN)=C(Ph)NMe2 (3a) as a mixture of isomers. The ferriophosphane Cp*(CO)(2)FeP[CH(CN)-CH2CN]-[CH(CN)-C(CN)=C(tBu)NMe2] (5) was isolated in less than 1% yield from the reaction of 1b and the alkene. The reaction of ferrioarsaalkene Cp*(CO)(2)FeAs=C(Ph)NMe2 (6) and fumaronitrile gave rise to the formation of the ferrioarsetane Cp*(CO)(2)FeAsCH(CN)-CH-(CN)-C(Ph)NMe2 (7), which unlike 2a resists ring opening in solution