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

The oxalato complexes [Ru2(μ-η -C2O4)Cl2(η -p-PrC6H4Me)2] 1 and [Ru(η -C2O4)(NH3)(η -p-PrC6H4Me)] 2 have been prepared from the reaction of ammonium oxalate with [{RuCl2(η -p-PrC6H4Me)}2] and [Ru(H2O)3(η-p-PrC6H4Me)] , respectively. With triphenylphosphine, 1 reacted to give [Ru2(μ-η -C2O4)(PPh3)2(η -p-PrC6H4Me)2] 21 3, while 2 gave [Ru(η-C2O4)(PPh3)(η -p-PrC6H4Me)] 4. The dichloro complex 1 can also be converted into the cationic dimethanol complex [Ru2(μ-η -C2O4)(MeOH)2(η -p-PrC6H4Me)2] 21 5 by precipitation of the chloride with a silver salt in methanol. Complex 5 reacted with 4,49-bipyridine to afford a novel tetranuclear metallomacrocycle [Ru4(μ-η -C2O4)2(μ-η 1 :η-bipy)2(η -p-PrC6H4Me)4] 41 6 with alternating oxalato and 4,49bipyridine bridges. The reaction between 1 and azide yielded the known azido-bridged complex [{Ru(μ-η-N3)Cl(η-p-PrC6H4Me)}2] 7. The molecular structures of 1 (two conformational isomers), 4, 5 and 6 have been solved by X-ray crystallography.