Behaviour of α-functional organotransition metals. Synthesis, characterisation and some reactions of 1-acetoxyalkyl derivatives of iron(II) and molybdenum(II)

Abstract

Acetoxyalkyl metal derivatives M(C 5H 5)(CO) n [CHROC(O)Me] [M = Fe, n = 2; M = Mo, n = 3; R = H, Me] are readily prepared by reaction of bromoalkylacetates with the appropriate cyclopentadienylcarbonylmetallate anion. The complexes are characterised by their NMR ( 1H and 13C) and IR parameters and by mass spectrometry. The acetoxyethyl species are thermally labile via β-hydrogen transfer. Treatment of acetoxymethyl complexes with protic acids leads to carbon-oxygen cleavage and release of acetic acid; HCl affords chloromethyl complexes, carboxylic acids yield new carboxylatomethyl derivatives, HBF 4 leads to decomposition. The metalloesters are resistant to hydrolysis, transesterification and carboxylate displacement by nucleophiles (HO −, MeO −, H 2N − Et 2N −). Migratory insertion of CO could not be induced.