Polymerizable group 4 ansa-cyclopentadienyl-amido catalysts for the copolymerization of ethylene with 1-octene

Selective Incorporation of Primary Amines into a Trizirconium Imido System and Catalyic Cyclization of Aminoalkynes

The trinuclear zirconium imido complex [{LZr(NMe₂)}₃] (2, L = C₅Me₄CH₂CH₂N) was synthesized by amine elimination between Zr(NMe₂)₄ and endo-olefinic isomers of (tetramethylcyclopentadienyl)ethanamine (LH₃) (1). To study the fundamental reactivity of the trizirconium system, reactions of 2 with primary amines were examined. Selective incorporations of the primary amines were observed, depending on steric and electronic natures of the amine substrates. The amine-incorporated complexes [(LZrNHR)(LHZrNHR)(LHZr)(μ-NHR)(μ₃-NR)] (3, R = Pr, Et), [(LZrNHR)₂(LHZr)(μ-NR)] (4, R = Pr, i-Bu), [(LZr)₂(LZrNMe₂)(μ-NR)] (5, R = neo-Pen), and [(LZr)(LZrNHAr)(LH₂Zr)(μ-NAr)₂] (6, Ar = Ph, C₆H₄-4-Br, C₆H₄-4-OMe) were structurally characterized by NMR and XRD analysis and showed several coordination modes of the substrate nitrogen ligands: i.e., terminal amides, bridging amides, and bridging imides but not terminal imides. Thermolysis of a mixture of 3 and 4 led to C-H bond activation, giving rise to the zirconaaziridines [{LZr(η²-NCHR)}(LZr)(LHZr)(μ-NHCH₂R)] (12, R = Et, Me). Complex 2 proved to be a competent precatalyst in the hydroamination of the aminoalkynes (H₂NCH₂CR¹₂CH₂C≡CR²) (13, R¹ = H, R² = Bu, Ph, t-Bu; 14, R¹ = Me, R² = Et, Ph). Stoichiometric or semicatalytic reactions of 2 and the aminoalkynes were studied to explore the reactivity of in situ formed Zr₃ species.