A DFT Mechanistic Study on Ethylene Tri‐ and Tetramerization with Cr/PNP Catalysts: Single versus Double Insertion Pathways. Issue 47 (10th October 2016)

• Record Type: Journal Article
• Authors: Britovsek, George J. P.; McGuinness, David S.
• Is Part Of: Chemistry. Volume 22:Issue 47(2016)
• Page Start: 16891
• Page End: 16896
• Publication Date: 2016-10-10
• Subjects: chromium -- homogeneous catalysis -- oligomerization -- tetramerization -- trimerization; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201603909
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The mechanism of ethylene trimerization and tetramerization with a chromium–diphosphinoamine (Cr–PNP) catalyst system has been studied by theoretical (DFT) methods. Two representative ligands have been explored, namely Ph2 PN(Me)PPh2 and ( o ‐MeC6 H4 )2 PN(Me)P( o ‐MeC6 H4 )2 . Calculations on the former ligand reveal how a combination of single and double ethylene insertion mechanisms may lead to 1‐hexene, 1‐octene and the major side products (cyclopentanes and n ‐alkanes). For the latter ligand, introduction of o ‐alkyl substitution leads to a more sterically congested active species, which suppresses the available pathways for tetramerization and side product formation. Hence, the high selectivity of o ‐aryl substituted PNP ligands for trimerization can be rationalized. Abstract : Calculating the C2 times table : The mechanism of ethylene trimerization and tetramerization with chromium–diphosphinoamine complexes, and the influence of ligand sterics, was investigated through a density functional theoretical study (see scheme).