IR spectra and structures of saturated ruthenium cluster carbonyl cations Run(CO)m+ (n = 1-6)

Abstract

A series of saturated ruthenium cluster carbonyls (Ru(CO)5+, Ru2(CO)9+, Ru3(CO)12+, Ru4(CO)14+, Ru5(CO)16+ and Ru6(CO)18+) have been synthesized in the gas phase and subsequently characterized by infrared spectroscopy. Their size-specific IR spectra in the region of the carbonyl stretch vibration (1900-2150 cm−1) and in the region of the Ru-C-O bending modes (420-620 cm−1) are obtained by infrared multiple photon dissociation spectroscopy. The structures of these cluster carbonyls are assigned by comparison with results from density functional calculations. A multitude of differently activated CO ligands are identified in these cationic cluster carbonyls, reaching from terminal, over non-symmetrically bridging (semi-bridging) ligands with varying degrees of interaction to additional Ru atoms towards symmetrically bridging CO ligands.