Mono-, di- and tetra-nuclear p-cymeneruthenium complexes containing oxalato ligands

The oxalato complexes Ru2 (µ-η4-C2O4) Cl2 (η6-p-PriC6H4Me) 2 1 and Ru (η2-C2O4) (NH3) (η6-p-PriC6H4Me) 2 have been prepared from the reaction of ammonium oxalate with RuCl2 (η6-p-PriC6H4Me) 2 and Ru (H2O) 3 (η6-p-PriC6H4Me) 2+, respectively. With triphenylphosphine, 1 reacted to give Ru2 (µ-η4-C2O4) (PPh3) 2 (η6-p-PriC6H4Me) 22+ 3, while 2 gave Ru (η2-C2O4) (PPh3) (η6-p-PriC6H4Me) 4. The dichloro complex 1 can also be converted into the cationic dimethanol complex Ru2 (µ-η4-C2O4) (MeOH) 2 (η6-p-PriC6H4Me) 22+ 5 by precipitation of the chloride with a silver salt in methanol. Complex 5 reacted with 4, 4′-bipyridine to afford a novel tetranuclear metallomacrocycle Ru4 (µ-η4-C2O4) 2 (µ-η1∶η1-bipy) 2 (η6-p-PriC6H4Me) 44+ 6 with alternating oxalato and 4, 4′-bipyridine bridges. The reaction between 1 and azide yielded the known azido-bridged complex Ru (µ-η1-N3) Cl (η6-p-PriC6H4Me) 2 7. The molecular structures of 1 (two conformational isomers), 4, 5 and 6 have been solved by X-ray crystallography.