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.