| Abstract: | Preparation and Properties of Soluble and Polysiloxane-Supported (Ether-Phosphine)ruthenium(II) Complexes Phosphine-modified Polysiloxanes of the type x SiO2 · SiO3/2(CH2)6P(Ph)R] (x = 0 – 3, I–IV ) were prepared by hydrolytic condensation of (MeO)3Si(CH2)6P(Ph)R 1 ; R = CH2CH2OMe ( a ), CH2C4H7O ( b ), CH2C4H7O2 ( c ), Ph ( d )]. Crosslinking was achieved by cocondensation of 1 and Si(OEt)4. 2 SiO2 · SiO3/2(CH2)6P(Ph)CH2CH2OMe] ( IIIa ) was investigated by means of 31P and 29Si CP-MAS-NMR-spectroscopy, especially in view of a quantification of silyl species which revealed the following ratios: T2:T4:Q2:Q3:Q4 = 76:158:48:135:82. Reaction of RuCl2(PPh3)3 with 3 moles of 1a gave fluxional RuCl2(P∩O)(P～O)2 ( 4a ). From its temperature dependent 31P{1H}-NMR spectrum the temperatures of coalescence and the corresponding activation enthalpies could be estimated at -25°C (46 kJ · mol?1) and +20°C (55 kJ · mol?1). Soluble 1a-d as well as their insoluble counterparts I-IV were treated with RuCl2(CO)2]n to give all-trans-RuCl2(CO)2(PR3)2 ( 6 ). On heating (120°C) 6 could be transformed into isomeric cis, cis, trans-RuCl2(CO)2(PR3)2 ( 7 ). Decarbonylation occurred on irradiation of 6 . Polysiloxane-supported ruthenium complexes were proved to be active in the heterogeneous hydrogenation of crotonaldehyde. Thus, at p(H2) = 50 bat, T = 120°C, reaction time = 190 min, and at a molar ratio of aldehyde: Ru = 250:1, all-trans-RuCl2(CO)2(P～O)2 ( 6f , O,P = IIIa ) effected a conversion of 50%, crotyl alcohol being formed in comparatively high selectivities. Moreover, no loss of metal or ligand from the support could be observed. |
