Essentially Molecular Metal Complexes Anchored to Zeolite β: Synthesis and Characterization of Rhodium Complexes and Ruthenium Complexes Prepared from Rh(acac)(η2-C2H4)2andcis-Ru(acac)2(η2-C2H4)2

Abstract

Mononuclear complexes of rhodium and of ruthenium, Rh(acac)(η2-C2H4)2 and cis-Ru(acac)2(η2-C2H4)2 (acac = C5H7O2−), were used as precursors to synthesize metal complexes bonded to zeolite β. Infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectra show that the species formed from Rh(acac)(η2-C2H4)2 was Rh(η2-C2H4)2+, which was bonded to the zeolite at aluminum sites via two Rh−O bonds. Reaction of this supported rhodium complex with CO gave the supported rhodium gem-dicarbonyl Rh(CO)2+, which was characterized by two νCO bands in the IR spectrum, at 2048 and 2115 cm−1, that were sharp (fwhm of 2115-cm−1 band = 5 cm−1), indicating a high degree of uniformity of the supported species. Nearly the same result was observed (Liang, A. et al. J. Am. Chem. Soc. 2009, 131, 8460) for the isostructural rhodium complex supported on dealuminated HY zeolite, which was characterized by frequencies of the νCO bands that were 4 and 2 cm−1, respectively, greater than those characterizing the zeolite β-su...