Abstract

The dicationic T-silyl functionalised bis(acetonitrile)(dppp)palladium(II) complex 2(T⁰) (see Scheme 1) was sol–gel processed with different amounts (y) of the co-condensation agent MeSi(OMe)₂(CH₂)₆(MeO)₂SiMe (D⁰-C₆-D⁰) to give the new stationary phases 2a–h(Tⁿ)(Dⁱ-C₆-Dⁱ)_y (y = 0, 5, 10, 15, 20, 40, 80, and 100; n = 0–3, i = 0–2). The polysiloxane matrices and the integrity of the palladium(II) complex centres were investigated by means of solid state NMR (²⁹Si, ¹³C, ³¹P) and EXAFS spectroscopy. Dynamic NMR investigations show an increasing mobility of the hybrid polymers on going from y = 0 to 10. For higher amounts of the co-condensation agent MeSiO_i/2(OX)_{2 − i}(CH₂)₆O_i/2(XO)_{2 − i}SiMe (Dⁱ-C₆-Dⁱ) the mobility tends toward that of a matrix consisting of Dⁱ-C₆-Dⁱ (T/D = 0) only. NMR experiments in suspension give further evidence for considerable mobility of the interphases (formed by the penetration of stationary and mobile phases on a molecular scale). Model reactions of 2a(Tⁿ) with different isocyanides in the interphase point to almost complete accessibility of the palladium(II) centres, even if the reactants carry sterically demanding substituents (e.g.t-Bu). The activity of the hybrid catalysts 2a–h(Tⁿ)(Dⁱ-C₆-Dⁱ)_y in the ethene/CO copolymerisation is markedly dependent on the temperature and the amount y of the co-condensation agent. A maximum of activity [1600 g(ECO) g(Pd)⁻¹ h⁻¹] is achieved with y = 10 which is 75% of the activity of the analogous homogeneous catalyst.