... DOI: 10.1039/C001630F (Communication) Dalton Trans., 2010, 39, 5605-5607 ... Organometallic ruthenium(II) complexes, in particular [(η 6 -arene)RuL 2 (H 2 O)] 2+ with L 2 being a bidentate P,P-, P,N-, N,O- or N,N-ligand have been shown to catalyse D–A reactions in ...