Electrochemistry and spectroscopy of organometallic terpyridine nickel complexes.

Organonickel complexes [(R'terpy)Ni(aryl)]X (R'terpy = derivatives of 2,2';6',2''-terpyridine; aryl = 2,6-dimethylphenyl = Xyl or 2,4,6-trimethylphenyl = Mes; X = Br or PF(6)) have been investigated by multiple electrochemical methods as well as combined electrochemical/spectroscopic techniques (spectroelectrochemistry). Reversible electrochemical reduction fills successively pi* orbitals in the terpy ligand. Some of the occurring species were characterized spectroscopically (EPR and UV/vis/NIR spectroelectrochemistry). The presumably nickel-centered oxidation occurs irreversibly.