Towards the synthesis of a metal hamburger complex: the interaction of the PPh2(CH2)3Ph ligand with ruthenium clusters

Ruthenium clusters were reacted with the chelating arene ligand PPh2(CH2)3Ph. First, the phosphorous atom was coordinated to Ru6, Ru5 and Ru3 clusters, and the products of simple addition were fully characterised. A second (and third in the case of Ru3) equivalent of the ligand was then successfully added to the obtained species. Attempts to coordinate the ‘dangling’ benzene ring led to a Ru6 derivative, where a phenyl ring directly bound to the P atom reacted with the cluster, instead of the terminal one. The crystal structures of the compounds [Ru6C(CO)16PPh2(CH2)3Ph] (3), [Ru3(CO)9{PPh2(CH2)3Ph}3] (9), and [Ru6C(CO)13PPh2(CH2)3Ph] (10) were determined by X-ray diffraction. The former two consist of the intact cluster core with either one or three ligands bonded via the P atom, while the latter has additionally one of the phenyl rings on the phosphorous connected to the cluster in a η6 bonding mode.