Highly selective nickel ethylene oligomerization catalysts based on sterically hindered tris(pyrazolyl)borate ligands

Fábio A. Kunrath, Roberto F. De Souza, Osvaldo L. Casagrande, Neil R. Brooks, Victor G. Young

Research output: Contribution to journalArticle

93 Scopus citations

Abstract

The reaction of TlTp′ (Tp′ = HB(3-mesitylpyrazolyl)3- (TpMs), HB(3-mesitylpyrazolyl)2(5-mesitylpyrazolyl)- (TpMs*)) with NiCl2·6H2O affords TpMsNiCl (1) and TpMs*NiCl (2) in good yield. The compound 2 undergoes an isomerization process to form [{TpMs**}NiCl]2 (3) (TpMs**= HB(5-mesitylpyrazolyl)2(3-mesitylpyrazolyl)-) in 68% yield. Treatment of the tris(pyrazolyl)-borate nickel compounds 1 and 2 with alkylaluminum cocatalysts such as methylalumoxane (MAO) and trimethylaluminum (TMA) in toluene generates active catalysts for ethylene oligomerization. The compound 1 shows turnover frequencies in the range of (2.2 - 43.1) × 103 h-1. Oligomerization reaction conditions can be adjusted that lead to selectivities as high as 81% for butene-1.

Original languageEnglish (US)
Pages (from-to)4739-4743
Number of pages5
JournalOrganometallics
Volume22
Issue number23
DOIs
StatePublished - Nov 10 2003

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