Bis-hydroxylaminato group 4 half-sandwich complexes—syntheses, structures and polymerisation activity studies

Abstract

The methylene- and ethylene-bridged bis-hydroxylamines HONMe(CH₂)_nNMeOH (n = 1, 2) were reacted with [Cp*TiCl₃], [Cp*ZrCl₃] and [Cp*HfCl₃] in the presence of MeLi to give the complexes [Cp*TiMe{(η²-ONMe)₂CH₂}] (1), [Cp*TiMe{(η²-ONMeCH₂)₂}] (2), [Cp*ZrMe{(η²-ONMeCH₂)₂}] (3) and [Cp*HfMe{(η²-ONMeCH₂)₂}] (4). The reaction of 2 with AlMe₃ afforded the adduct [Cp*TiMe{η²-[O(AlMe₃)NMe]CH₂CH₂-η²-(NMeO)}] (2·AlMe₃). The compounds were characterised by NMR spectroscopy, elemental analyses and mass spectrometry. Their crystal structures were determined by X-ray diffraction. In each case, all four donor atoms of the [2 + 2]-dentate ligands coordinate in a η²-manner to the organometallic [Cp*MMe] complex fragments. The polymerisation reactions of ethylene and propylene catalysed by 2 activated with methylalumoxane (MAO) were examined.