NUCLEAR-MAGNETIC-RESONANCE STUDIES ON THE STRUCTURE OF RUTHENIUM(II) COMPLEXES OF DI-2-PYRIDYLAMINE IN DMSO SOLUTION

The complete assignments of the H-1 and C-13 NMR spectra of [Ru(bpy)n(Hdpa)3-n]2+ (n=0-2) have been carried out on the basis of proton-proton coupling constants, H-H COSY, C-H COSY, and the aromatic ring-current effects of the ligand. The observed aromatic ring-current shifts of the assigned H-1 NMR signals were compared with the calculated ones by using a current-loop model. The flapping of the Hdpa ligands showed that the structures of [Ru(bpy)2(Hdpa)]2+, [Ru(bpy)(Hdpa)2]2+, and [Ru(Hdpa)3]2+ in solution have apparent C2, C2, and D3 symmetries, respectively.