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(mu(3)-OtBu)(2)(mu(2)-OtBu)(3)-(mu-OtBu)(4)(THF)(2)] (1) and the monomeric precursor [Nd(OC(6)H(2)tBU(2)-2,6-Me-4)(3)(THF)] (2) were used in association with [Mg(CH2SiMe3)(2)(Et2O)] (3). The new heterodimetallic complex [(THF)Nd(mu(3)-OtBu)(2)(mu(2)-OtBu)(2)(OtBu)Mg-2(CH2TMS)(2)] (4) and the alkyllanthanide complex [Nd(OC(6)H(2)tBu(2)-2,6-Me-4)(2)(CH2SiMe3) (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)"/MgR2 mixture, consistent with the observed behavior of these combinations in olefin polymerization. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.