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.