Ligand-metal interaction in transition-metal complexes with tripodal polyaza ligands

Five complexes ([Cu(tpc)]²⁺ 1, [Cu(tpa)]²⁺ 2, [Co(tpa)]²⁺ 3, [Fe(tpa)]²⁺ 4 and [Mn(tpa)]²⁺ 5) (tpc=N, N’, N"-tris[(2-pyridyl)methyl]-1,4,7-triaza-cyclononane(L1) and tpa=tris[2-((2-pyridyl) methyl-imino)ethyl]amine(l2)) were synthesized and characterized. The crystal structures of 1, 3 and 4 were determined by X-ray crystallography. Electrochemical investigations over two cupric complexes reveal that 2 has a less negative redox potential than that of 1. Electronic spectra of 2, 3, 4 and 5 show that the distinction in metal ion results in a shift of the ligand-based π*→π transition. Foundation item: Supported by the Natural Science Foundation of Hubei province Biography: Yin Ye-gao (1950-), male, Associate professor, researching for the the synthsis and properties of tripodal polydentate ligands.