Novel Catalyst Systems Based on Cationic Palladium Cyclopentadienyl Complexes for the Polymerization of Norbornene and Norbornene Derivatives.

Results of studying the catalytic properties of systems based on complexes with [Pd(Cp)(L)n]m[BF4]m (where Cp = η5-C5H5; n = 2, m = 1: L = tris(ortho-methoxyphenyl)phosphine, triphenylphosphine, tris(2-furyl)phosphine (TFP); n = 1, m = 1: L = 1,1'-bis(diphenylphosphino)ferrocene, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,5-bis(diphenylphosphino)pentane; n = 1, m = 2 or 3: L = 1,6-bis(diphenylphosphino)hexane) in the addition homo- and copolymerization of norbornene (NB) and NB derivatives have been described. It has been found that these complexes can be activated with Lewis acids (BF3⋅OEt2 or AlCl3). The productivity of the [Pd(Cp)(PPh3)2][BF4]/BF3⋅OEt2 catalyst system in NB polymerization can achieve 188 800 molNB . The homopolymerization of 5-methoxycarbonylnorbornene and the copolymerization of NB with 5-methoxycarbonylnorbornene or 5-phenylnorbornene in the presence of BF3⋅OEt2 and [Pd(Cp)(L)2][BF4] (L = PPh3 or TFP) has been studied. A hypothesis for the formation of the catalyst via the intramolecular rearrangement of the η5-Cp ligand into the η1-Cp form upon interaction with a Lewis acid has been proposed. The structure of the [Pd(Cp)(TFP)2]BF4 complex (I) has been determined by X-ray diffraction (XRD) analysis. In the crystal structure of complex I, the coordination sphere of palladium is characterized by a slight distortion of the square planar geometry of the central atom, while the cyclopentadiyl moiety is in an eclipsed conformation. Based on XRD data, the steric hindrance of the TFP ligand has been determined (cone angle is 149°). [ABSTRACT FROM AUTHOR]