Synthesis, characterization and reactivity of the omega-haloalkyl complexes [(eta(5)-C5R5)W(CO)(3){(CH2)n(-)X}] (R = H, n = 3-7, X = Br and I; R = CH3, n = 3, 4, X = Br and I)

The new omega-bromoalkyl tungsten complexes [CpW(CO)(3){(CH2)(n)Br}] (n = 5 -7) and [Cp*W(CO)(3){(CH2)(n)Br)}] (n = 4) were prepared in good yields by the reactions of Na[CpW(CO)(3)] or Na[Cp*W(CO)(3)] with the appropriate dib romoalkanes. The iodoalkyl complexes [CpW(CO)(3){(CH2)(n)I}] (n = 3-7) and [Cp*W(CO)3{(CH2)(n)I}] (n = 3 and 4) were prepared by reacting [Cpw(CO)(3){ (CH2)(n)Br}] or [Cp*W(CO)(3){(CH2)(n)Br}] with sodium iodide, or by reactin g the Na[CpW(CO)(3)] with the appropriate diiodoalkanes. These new complexe s have been fully characterized by elemental analyses, IR, H-1-, C-13-NMR a nd mass spectroscopy. The thermal and electrochemical properties of some of the haloalkyl complexes are reported. The reaction of [CpW(CO)(3){(CH2)(3) Br}] with 3,5-dihydroxybenzyl alcohol gave both the mono- and the di-tungst en benzyl alcohol complexes [{Cpw(CO)(3)(CH2)(3)O-}{C6H3(OH)}-CH2OH] and [{ CpW(CO)(3)(CH2)(3)O-}(2)(C6H3)-CH2OH]. The later complex reacted with CBr4 and PPh3 to give the benzyl bromide complex [{CpW(CO)(3)(CH2)(3)O-}(2)(C6H3 )-CH2Br]. The reaction of [CpW(CO)(3){CH2)(3)Br}] with 1,1,1-trjs(4'-hydrox yphenyl)ethane gave the tri-nuclear tungsten complex [{CpW(CO)(3)(CH2)(3)O- (C6H4)}(3)-CCH3]. (C) 1999 Published by Elsevier Science S.A. All rights re served.