AN UNUSUAL HYDROGEN MIGRATION FROM A CYCLOPENTADIENYL TO A MU-CARBYNECARBON IN THE REACTION OF GRIGNARD-REAGENTS WITH [FE-2(CO)(2)(CP)(2)(MU-CO)(MU-CSME)]SO3CF3

Reaction of [Fe-2(CO)(2)(cp)(2)(mu-CO)(mu-CSMe)]SO3-CF3 CF3(1; cp = et a-C5H5) with Grignard reagents RMgCl (R benzyl, phenyl, isopropyl) for ms the alkylidene compounds [Fe-2(CO)(2)(cp)(C(5)H(4)R)(mu-CO){mu-C(SM e)H}] (2) and the corresponding cyclopentadiene complexes [Fe-2(CO)(2) (cp)(C(5)H(5)R)(mu-CO)(mu-CSMe)] (3). The latter complexes are the int ermediates in the formation of 2 which are formed by hydrogen migratio n from the C(5)H(5)R ring to the ILL-C carbyne carbon. The molecular s tructure of [Fe-2(CO)(2)(cp)(C(5)H(4)Bz)(mu-CO){mu C(SMe)H}] has been determined by X-ray crystallography. Spectroscopic properties of the c omplexes are also presented.