Electrochemical and spectroelectrochemical studies of complexes of 1,10-phenanthroline-5,6-dione

Electrochemical and spectroelectrochemical (UV–Vis, IR, EPR) of pd (pd = 1,10-phenanthroline-5,6-dione), Pt(N,N′-pd)Cl2, Pd(N,N′-pd)Cl2, [Ru(bpy)2(N,N′-pd)]Cl2 (bpy = 2,2′-bipyridine) and Pt(O,O′-pd)(PPh3)2, where N,N′ and O,O′ refers to coordination of pd to the metal centre via N and O atoms, respectively, reveals that the electron transfer processes between +0.5 and −1.25 V all occur at the pd ligand in agreement with DFT calculations. The two CO groups carry a significant amount of the negative charge in mono-reduced pd1−. The mode of coordination of pd has a greater influence on its redox chemistry than the metal centre or the ancillary ligands