- Synthesis, immobilization, MAS and HR-MAS NMR of a new chelate phosphine linker system, and catalysis by rhodium adducts thereof
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A new class of tridentate phosphine ligands with the general formula [MeP{(CH2)xPPh2}3]+I - (x=4, 7, 11) and [MeP(CH2PPh2) 3]+OTf-, has been synthesized and fully characterized. The linkers have been immobilized on silica with their phosphonium moieties via electrostatic interactions, and their mobility and leaching has been studied by solid-state HR-MAS (high-resolution magic angle spinning) NMR in various solvents. Immobilized Wilkinson-type rhodium complexes have been obtained by ligand exchange with the surface-bound linkers. The activities and lifetimes of the catalysts have been tested with respect to the hydrogenation of 1-dodecene. The rhodium catalyst precursor bound by the immobilized linker [MeP{(CH2)7PPh2} 3]+I- led to material with the highest activity and lifetime, and it could be recycled for 30atimes in a batchwise manner. The other catalysts show shorter lifetimes. For all catalysts the formation of rhodium nanoparticles with a narrow size distribution around 4anm has been proven.
- Guenther,Reibenspies,Bluemel
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experimental part
p. 443 - 460
(2011/04/16)
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- Highly atom-economic one-pot formation of three different C-P bonds: General synthesis of acyclic tertiary phosphine sulfides
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The reaction of benzothiadiphosphole 1 with an equimolar mixture of R 1MgBr and R2MgBr gave intermediate A′, which, after only 4-5 min, was treated with an equimolar amount of R3MgBr, giving the asymmetric phosphine PR1R2R3 in 45% overall yield (75-80% yield when R1 = R2 and 85-90% yield when R1 = R2 = R3) and the byproduct 6 in 90% yield. The treatment of 6 with PCl3 quantitatively regenerates the starting reagent 1. Treatment of the phosphines with elemental sulfur gave the corresponding sulfides.
- Baccolini, Graziano,Boga, Carla,Mazzacurati, Marzia
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p. 4774 - 4777
(2007/10/03)
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- Preparation of organohalosilanes
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In an industrial process for preparing organohalosilanes by reacting metallic silicon particles with an organohalide in the presence of a copper catalyst, a contact mass composed of the metallic silicon and the catalyst further contains an effective amount of a phosphine chalcogenide compound. The invention drastically increases the silane formation rate and the utilization of silicon without lowering the selectivity of useful silane.
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