Influence of alkoxy ligands on the Cp-Al bonding mode in [Cp2Al-mu-OR](2) from X-ray crystallographic and Al-27-NMR spectroscopic solution studies

摘要

The dicyclopentadienylaluminium alkoxides of general formula [Cp2Al-mu-OR](2) where R = Me, Et, n-Bu, i-Bu, CH(2)t-Bu, s-Bu, CH2Ph, C6H4-4-t-Bu (1-8) were prepared by reacting CpNa with ROAlCl2, at the molar ratio 2:1, respectively (2-8) or from the reaction Of Cp3Al with alcohol (1). The compounds were characterised by multinuclear NMR (H-1, C-13, Al-27) method. The molecular structures of compounds 2, 5 and 6 were determined by X-ray crystallography. The Cp-Al bonding mode in dicyclopentadienylaluminium alkoxides regarding the steric demands of alkoxy groups is discussed based on Al-27-NMR chemical shifts and structural data obtained. The meaningful correlation between Cp ring-slippage and Al-27-NMR chemical shifts was observed. (C) 2003 Elsevier Science B.V. All rights reserved. [References: 35]