Silica nanoparticles (SiNPs) were chosen as a solid support material for the immobilization of a new Wilkinson's-type catalyst. In a first step, polymer molecules (poly(triphenylphosphine)ethylene (PTPPE); 4-diphenylphosphine styrene as monomer) were grafted onto the silica nanoparticles by surface-initiated photoinferter-mediated polymerization (SI-PIMP). The catalyst was then created by binding rhodium (Rh) to the polymer side chains, with RhCl3⋅x H2O as a precursor. The triphenylphosphine units and rhodium as Rh(I) provide an environment to form Wilkinson's catalyst-like structures. Employing multinuclear ((31)P, (29)Si, and (13)C) solid-state NMR spectroscopy (SSNMR), the structure of the catalyst bound to the polymer and the intermediates of the grafting reaction have been characterized. Finally, first applications of this catalyst in hydrogenation reactions employing para-enriched hydrogen gas (PHIP experiments) and an assessment of its leaching properties are presented.

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A novel strategy for the immobilization of Wilkinson's catalyst on silica nanoparticles is presented, employing pyridyl linkers as anchoring groups. The coordination binding of the catalyst to the pyridyl linker via ligand exchange of the trans‐phosphine group is verified by 1 D and 2 D solid‐state NMR spectroscopy. Catalytic activities are monitored by GC employing the hydrogenation of styrene as model reaction, and the leaching properties as well as the robustness of the catalyst are investigated. The resulting immobilized catalyst shows high catalytic activity, which is within a factor of three comparable to the homogeneous catalyst, and excellent stability in leaching tests. Finally, it is efficient to produce hyperpolarization in solution by employing parahydrogen‐enriched hydrogen gas for hydrogenation.

The synthesis of a novel immobilized Wilkinson’s catalyst [SiO2∼PvPy-Wilk] is presented. The support material of this catalyst consists of silica particles that are modified with polymer brushes carrying pyridyl moieties that enable the coordination of Wilkinson’s catalyst. The synthesis of this catalyst is monitored by 1D and 2D multinuclear solid-state NMR techniques to confirm the success of the immobilization. The [SiO2∼PvPy-Wilk] catalyst is then tested in the hydrogenation of styrene, and its reusability is inspected showing that significant structural changes after several reaction cycles yield an activation of the catalyst. Finally, the catalyst is tested in PHIP experiments giving rise to about 200-fold enhancement of the signals of the hydrogenation product ethylbenzene.

Catalysts and Nanoparticles -[146 refs.]. -(GUTMANN, T.; GRUENBERG, A.; ROTHERMEL, N.; WERNER, M.; SROUR, M.; ABDULHUSSAIN, S.; TAN, S.; XU, Y.; BREITZKE, H.; BUNTKOWSKY, G.; Solid State Nucl. Magn. Reson. 55-56 (2013) 1-11, http://dx.