Stabilities and Near UV. Charge transfer spectra of binuclear and heterobinuclear complexes of N,N′-bis-[2-(2-pyridylmethyl-amino)-ethyl]-oxamide with transition-metal ions

The formation of complexes of N,N′‐bis‐[2‐(2‐pyridylmethyl‐amino)‐ethyl]‐oxamide (PAOH2) with Mn2+, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+ has been studied potentiometrically and spectrophotometrically. Besides mononnclear species, PAOH2 forms the binuclear or heterobinuclear complexes Cu2(PAOH2)4+, Cu2PAO2+, Zn2PAO2+, CuNiPAO2+, and probably CuZnPAO2+ Some of these five compounds show an UV. absorption band near 350 nm reminiscent of that to dimeric copper acetate. The results suggest that charge transfer from the oxamidato group to Cu2+ is responsible for the near UV. absorption.