Synthesis, Immobilization, MAS and HR‐MAS NMR of a New Chelate Phosphine Linker System, and Catalysis by Rhodium Adducts Thereof

Abstract

AbstractA 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 30 times in a batchwise manner. The other catalysts show shorter lifetimes. For all catalysts the formation of rhodium nanoparticles with a narrow size distribution around 4 nm has been proven.