Synthesis, characterization and reactions of the transition metal halogenoalkyl carbocation complexes [Cp(CO)2M{η2-CH2CH(CH2)nX}] PF6(n=1-8, 10, M = Fe; n=3, 4 M = Ru; X = Br, I)

The halogenoalkyl complexes [Cp(CO)(2)M{(CH(2))(n)X}] (n = 3-10, 12, M = Fe; n = 5, 6, M = Ru, X = Br, I) react with Ph(3)CPF(6) in dry CH(2)Cl(2) to give the corresponding carbocation complexes [Cp(CO)(2)M{eta(2)-(CH(2)CH(CH(2))(n) (2)X}] PF(6) in high yields. NMR evidence indicates that the metals form metallacyclopropane type structures with the carbocation ligand. The reactions of some of the cationic complexes with NaI, PPh(3), Na[Cp(CO)(2)Fe] and Et(3)N are discussed. NaI and Na[Cp(CO)(2)Fe] displace the halogeno-olefin, while PPh(3) adds at the beta-CH(delta+) giving the unstable phosphonium adducts [Cp(CO)(2)Fe{CH(2)CH(PPh(3))(CH(2))(n) (2)X}] PF(6) which decompose to the halogeno-olefins and the cationic PPh(3) complex [Cp(CO)(2)Fe(PPh(3))](+). Et(3)N causes allylic deprotonation forming internal olefin complexes of the type [Cp(CO)(2-) Fe{CH(2)CH=CH(CH(2))n (3)X}] PF(6). (C) 2008 Elsevier B.V. All rights reserved.