856891-99-1Relevant academic research and scientific papers
Synthesis, structural characterization, and catalytic properties of group 4 metal complexes incorporating a phosphorus-bridged indenyl-carboranyl constrained-geometry ligand
Wang, Hong,Chan, Hoi-Shan,Okuda, Jun,Xie, Zuowei
, p. 3118 - 3124 (2008/10/09)
Interaction of iPr2NP(C9H 7)(C2B10H11) with 1 equiv of M(NR2)4 in toluene gave constrained-geometry group 4 metal amides [η5:σ-iPr2NP(C 9H6)(C2B10H10)]M(NMe 2)2 (R = Me, M = Ti (1), Zr (2), Hf (3); R = Et, M = Hf (4)) in good yields. Compound 2 reacted with 3 equiv of PhNCO to produce the tri-insertion product [η5:σ-iPr 2NP(C9H6)(C2B10H 10)]Zr[η2-OC(NMe2)NPh] [η 2-OC(NMe2)N(Ph)C=(NPh)O] (5). No further insertion reaction occurred with another equivalent of PhNCO. Instead, the trimer (PhNCO)3 was isolated. Compound 2 reacted with 2 equiv of n-BuLi in toluene to afford, after recrystallization from DME/toluene, the dilithium salt [Li(DME)3] [η5:σ-iPr 2NP(C9H6)(C2B10H 10)Li(DME)] (6). An equimolar reaction of 2 with acetylacetone resulted in the formation of Zr(acac)4. 2 exhibited an ethylene polymerization activity of 3.7 × 103 g PE mol-1 atm-1 h-1 upon activation with MMAO. Furthermore, 2 was also able to efficiently initiate the polymerization of ε-caprolactone to give polymers of high molecular weights (Mn > 40 000) and low polydispersities (MwMn 1.4) through the action of the nucleophilic amido-nitrogen atom, which represents the first example of the polymerization of ε-caprolactone catalyzed by group 4 metal amides.
