Synthesis, spectroscopy, and electrochemistry of homo- and hetero-leptic ruthenium(II) complexes of new pyrazole-containing bidentate ligands

Heteroleptic [Ru(bipy)2(L–L′)]2+ and homoleptic [Ru(L–L′)3]2+ complexes, where bipy = 2,2′-bipyridine and L–L′ is one of nine new pyrazole-containing bidentate ligands, have been prepared. Full assignments have been made for the 1H and 13C n.m.r. spectra of the complexes in CD3CN and the origins of the co-ordination-induced shifts are discussed. The absorption spectra and redox properties of the complexes are also discussed.