Ruthenium Nanoparticles Inside Porous [Zn4O(bdc)3] by Hydrogenolysis of Adsorbed [Ru(cod)(cot)]: A Solid State Reference System for Surfactant Stabilized Ruthenium Colloids.

Felicitas Schröder, Daniel Esken, Mirza Cokoja, Maurits W. E. van den Berg, Oleg I. Lebedev, Gustaaf Van Tendeloo,  Bernadeta Walaszek, Gerd Buntkowsky, Hans-Heinrich-Limbach, Bruno Chaudret and Roland A. Fischer

J. Am. Chem. Soc. 130 (2008) 6119-6130

The gas-phase loading of [Zn4O(bdc)3] (MOF-5; bdc = 1,4 benzenedicarboxylate) with the volatile compound [Ru(cod)(cot)] (cod = 1,5-cyclooctadiene, cot = 1, 3, 5-cyclooctatriene) was followed by solid state 13C magic angle spinning (MAS)-NMR spectroscopy. Subsequent hydrogenolysis of the adsorbed complex inside the porous structure of MOF-5 at 3 bar and 150 °C was performed, yielding ruthenium nanoparticles in a typical size range of 1.5-1.7 nm imbedded in the intact MOF-5 matrix as confirmed by transmission electron microscopy (TEM) micrographs, selected area electron diffraction (SAED), powder X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS). The adsorption of CO molecules on the obtained Ru@MOF-5 nanocomposite was followed by IR. Solid state 2H-NMR measurements indicated MOF-5 being a stabilizing support with only weak interaction to the imbedded particles as deduced from the surprisingly high mobility of the surface Ru-D species in comparison to surfactant-stabilized colloidal Ru nanoparticles of similar sizes. Surprisingly, hydrogenolysis of the [Ru(cod)(cot)]3.5@MOF-5 inclusion compound at milder condition of 25 °C however, does not lead to the quantitative formation of Ru nanoparticles. Instead, formation of a ruthenium-cyclooctadiene complex with the arene moiety of the bdc linkers of the framework takes place as revealed 13C MAS-NMR spectroscopy, XRD and TEM.