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