Easily available niobium(V) mixed chloro‐alkoxide complexes as catalytic precursors for ethylene polymerization

Abstract

AbstractThe dinuclear [NbCln(OR)(5‐n)]2 (n = 4, R = Et, 1; n = 4, R = CH2Ph, 2; n = 3, R = Et, 3; n = 2, R = Et, 4; n = 2, R = , 5), and [Nb(OEt)5]2, 6, and the mononuclear niobium compounds NbCl4[κ2OCH2CH(R′)OR] (R = Me, R′ = H, 7; R = Et, R′ = H, 8; R = CH2Cl, R′ = H, 9; R = CH2CH2OMe, R′ = H, 10; R = R′ = Me, 11), NbBr4[κ2OCH2CH2OMe], 12, and NbCl3(κ2OCH2CH2OMe)(κ1OCH2CH2OMe), 13, were tested in ethylene polymerization. Optimized reaction conditions included the use of D‐MAO as co‐catalyst and chlorobenzene as solvent at 50 °C. Complex 7, whose X‐Ray structure is described here for the first time, exhibited the highest activity ever reported for a niobium catalyst in alkene polymerization [151 kgpolymer × molNb−1 × h−1 × bar−1]. Compounds 1, 3‐5, 8, 13 showed activities similar to that of 7. Linear polyethylenes (characterized by FT‐IR, NMR, GPC, and DSC analyses) with a broad polydispersivity were obtained. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011