A deuterium exchange reaction of the tris-(2,2′-bipyridine)ruthenium( II ) cation: evidence for the acidity of the 3,3′-protons

The first observation of deuterium exchange upon 2,2′-bipyridine (bipy) co-ordinated to ruthenium(II) is reported; the reaction of [Ru(bipy)3]2+ in (CD3)2SO with Na[OCD3] in CD3OD to yield [Ru([3,3′-2H2]-bipy)3]2+ is demonstrated to involve deprotonation of the co-ordinated bipy ligand at the slightly acidic 3,3′-positions, an acidity promoted by steric strain.