Triruthenium and Triosmium Carbonyl Cluster Complexes Containing Deprotonated Di(2-pyridyl)amine in Unusual Coordination Modes

The synthesis of the first trinuclear carbonyl clusters containing ligands derived from di(2-pyridyl)amine (Hdpa) has been achieved. Treatment of [Ru₃(CO)₁₂] or [Ru₃(CO)₁₀(MeCN)₂] with di(2-pyridyl)amine (Hdpa) gives the cluster complex [Ru₃(μ-Η)(μ-η³-dpa-C,N,N)(CO)₉] (1). The dpa ligand in this compound chelates a Ru atom through both pyridinic nitrogens while attached to another Ru atom through the C atom of a metalated pyridine ring, keeping the amino NH fragment uncoordinated. Curiously, the osmium compounds [Os₃(μ-Η)(μ-η²-dpa-N,N)(CO)₁₀] (2) and [Os₃(μ-Η)(μ₃-η²-dpa-N,N)(CO)₉] (3), which have been stepwise prepared from [Os₃(CO)₁₀(MeCN)₂] and Hdpa, contain edge-bridging (2) and face-capping (3) N-deprotonated dpa ligands coordinated through the N atom of a pyridine ring and the N atom of the original amino fragment.