Binary Neodymium Alkoxide/Dialkylmagnesium Polymerization Systems: Studies on the Nature of the Reaction Intermediates and Active Species

Attempts to identify the intermediates and/or active species generated from binary combinations of a lanthanide alk(aryl)oxide with a dialkylmagnesium reagent, which behave as efficient olefin polymerization systems, are reported. The well‐defined trinuclear complex [Nd 3 (μ 3 ‐O t Bu) 2 (μ 2 ‐O t Bu) 3 (μ‐O t Bu) 4 (THF) 2 ] ( 1 ) and the monomeric precursor [Nd(OC 6 H 2 t Bu 2 ‐2,6‐Me‐4) 3 (THF)] ( 2 ) were used in association with [Mg(CH 2 SiMe 3 ) 2 (Et 2 O)] ( 3 ). The new heterodimetallic complex [(THF)Nd(μ 3 ‐O t Bu) 2 (μ 2 ‐O t Bu) 2 (O t Bu)Mg 2 (CH 2 TMS) 2 ] ( 4 ) and the alkyllanthanide complex [Nd(OC 6 H 2 t Bu 2 ‐2,6‐Me‐4) 2 (CH 2 SiMe 3 )(THF) 2 ] ( 5 ) have been isolated and characterized in the solid state and in solution. Complex 4 is proposed to be a reaction intermediate in the active species formation, while complex 5 is the first alkyllanthanide species isolated from an “Ln(OR) 3 ”/MgR 2 mixture, consistent with the observed behavior of these combinations in olefin polymerization. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)