Palladium–Osmium Heterometallic Clusters Containing N‑Heterocyclic Carbene Ligands

The room-temperature reaction of [Os₃(CO)₁₂] with [PdCl­(allyl)­(NHC)], where NHC (N-heterocyclic carbene) = SIPr [N,N′-bis­(2,6-diisopropylphenyl)­imidazolidin-2-ylidene] or IPr [N,N′-bis­(2,6-diisopropylphenyl)­imidazolin-2-ylidene], afforded Pd–Os mixed metal clusters with formulas of [Pd_nOs₃(CO)₁₂(NHC)_n] (n = 1–3). These are the first examples of Pd–Os heterometallic clusters containing NHC ligands, and they have all been structurally characterized. In all these clusters, the metal cores are raftlike, with carbonyl ligands bridging all the Os–Pd edges.