The Contrasting Chemistry and Cancer Cell Cytotoxicity of Bipyridine and Bipyridinediol Ruthenium(II) Arene Complexes

The synthesis and characterization of ruthenium(II) arene complexes [(η6-arene)Ru(N,N)Cl]0/+, where N,N = 2,2′-bipyridine (bipy), 2,2′-bipyridine-3,3′-diol (bipy(OH)2) or deprotonated 2,2′-bipyridine-3,3′-diol (bipy(OH)O) as N,N-chelating ligand, arene = benzene (bz), indan (ind), biphenyl (bip), p-terphenyl (p-terp), tetrahydronaphthalene (thn), tetrahydroanthracene (tha) or dihydroanthracene (dha), are reported, including the X-ray crystal structures of [(η6-tha)Ru(bipy)Cl][PF6] (1), [(η6-tha)Ru(bipy(OH)O)Cl] (2) and [(η6-ind)Ru(bipy(OH)2)Cl][PF6] (8). Complexes 1 and 2 exibit CH (arene)/π (bipy or bipy(OH)O) interactions. In the X-ray structure of protonated complex 8, the pyridine rings are twisted (by 17.31°). In aqueous solution (pH = 2−10), only deprotonated (bipy(OH)O) forms are present. Hydrolysis of the complexes was relatively fast in aqueous solution (t1/2 = 4−15 min, 310 K). When the arene is biphenyl, initial aquation of the complexes is followed by partial arene loss. Complexes with arene =...