Photosubstitution reaction of a bidentate ligand in a Ru(II) complex in aqueous solution

The photosubstitution reaction of the bidentate ligand in [Ru(bpy)(2)(Me(2)bpy)](2+) (bpy = 2,2'-bipyridine, Me(2)bpy = 6,6'-dimethyl-2,2'-bipyridine) in aqueous solution was analyzed using density functional theory calculations. For comparison, the corresponding reaction path for [Ru(bpy)2(phen)](2+) (phen = 1,10-phenanthroline), which is photostable, was also examined. The results suggest that substitution of the Me(2)bpy ligand with an H2O molecule occurs to form [Ru(bpy)(2)(H2O)](2+) in the triplet metal-centered state. When the second H2O molecule coordinates to [Ru(bpy)(2)(H2O)](2+) in the ground state, the bis-aqua product [Ru(bpy)2(H2O)(2)](2+) is formed.