摘要:
Addition of [Li-2(THF)(4)][C(NPh)(3)] (2) to a THF solution of Cp*ZrCl3 (Cp* = C5Me5) yields, after recrystallization in Et2O, the zwitterionic species Cp*[C(NPh)(3)]ZrCl2Li(Et2O)(THF) (3). Treating 3 with excess methylaluminoxane (MAO) affords a homogeneous Ziegler-Natta catalyst for ethylene polymerization. Addition of LiNPh2 to 3 allows for Cl substitution to give the new product Cp*[C(NPh)(3)]Zr(NPh2)ClLi(THF)(2) (4). A single crystal diffraction study of 4 reveals that the [C(NPh)(3)] ligand is eta(2)-bound. The group 5 complex Cp*[C(NPh)(3)]TaMe2 (5) was prepared by addition of 2 to Cp*TaMe2Cl(OSO3CF3). The X-ray diffraction structure of 5 shows that the [C(NPh)(3)] ligand is eta(2)-bound to tantalum and that, when compared to 4, there is less electron delocalization across the inner core of [C(NPh)(3)]. (C) 1998 Elsevier Science B.V.