Monometallic and Bimetallic Titanium κ1-Amidinate Complexes as Olefin Polymerization Catalysts

Abstract

A series of cyclopentadienyl-κ1-amidinate titanium complexes Cp*Ti{NC(ArR)NiPr2}Me2 (ArR = 4-C6H4R, where R = H (1-Me), CF3 (5-Me), tBu (6-Me), or NMe2 (7-Me)) with different para-substituents in the amidinate ligand were synthesized and structurally characterized, along with three bimetallic analogues: 1,4-C6H4{C(NiPr2)N}2{Cp*TiMe2}2 (2-Me), 1,3-C6H4{C(NiPr2)N}2{Cp*TiMe2}2 (3-Me), and CH2{1,4-C6H4-C(NiPr2)N}2{Cp*TiMe2}2 (4-Me). 13C NMR spectroscopy, density function theory, and the quantum theory of atoms-in-molecules were used to evaluate the donor ability of the various NC(Ar R)NiPr2 ligands and the influence of the ArR group para-substituents. Reactions of 1-Me and certain homologues, as well as 2-Me, with borate and borane reagents [CPh3][BArF4] (ArF = C6F5), BArF3, in the absence or presence of Lewis bases or polar unsaturated substrates were carried out, forming adducts and migratory insertion products such as [Cp*Ti{NC(Ph)NiPr2}Me(THF)][BArF4], [Cp*Ti{NC(Ph)NiPr2}{MeC(NiPr)2}][BArF4], and [1,4-C6H...