HALOGENOALKYL COMPLEXES OF TRANSITION-METALS

This chapter focuses on halogenoalkyl transition metal complexes, particularly monohalogenoalkyl transition metal complexes. Halogenoalkyl transition metal complexes of type [LyM((CH2)nX)] (Ly = ligands, M = transition metal, X = C1, Br, I, or F, n ≥ 1) are less well known, although they have recently been recognized as a separate class of alkyl compounds. Complexes [LyM((CH2)nX)] can either be considered as simple examples of functionalized alkyl compounds of transition metals or as metal-substituted alkyl halides. Complexes of the type [LyMCH2X] can be useful precursors to methylene complexes [LyM=CH2]+ hydroxymethyl complexes [ LyMCH2OH] and methylene-bridged complexes LyMCH2M'Lx all of which have been implicated in many catalytic processes. The monohalogenoalkyl complexes have a functionality on carbon, they have additional reactivity potential compared to the alkyl analogs. Thus, the halogenoalkyl complexes show interesting and novel chemistry and can be used, for example, as precursors for many important classes of compounds—including acyclic and cyclic carbene complexes, homo- and heterobimetallic hydrocarbon-bridged compounds, as well as a range of other important functionalized alkyl compounds. © 1991 Academic Press, Inc.