μ-Carbonyl-bis(carbonyl{η5-[tricarbonyl(η6-2-methylindenyl)chromium(0)]rhodium(III)})(Rh—Rh)

Abstract

The structure of the title complex, [Cr2Rh2(C10H9)2(CO)9], was solved by single-crystal X-ray diffraction analysis in the P21/c space group. The crystal shows two units of the tetrametallic complex in the asymmetric unit. The most remarkable features of this new compound are the asymmetric bonding of the RhIII atom to the indenyl ligand, which can be formulated in terms of an η2;η3 coordination rather than η5, and the Rh—Rh distances of 2.6756 (6) and 2.6737 (6) Å that are characteristic of an intermetallic interaction supported by a bridging carbonyl ligand. The infrared spectroscopic signature informs of its clear bridging feature characterized by a significantly elongated C=O bond length compared to those in the two Rh-bound `terminal' carbonyl ligands.