Synthesis, structure and redox properties of a new ruthenium(II) complex containing the flexible tridentate ligand N,N-bis(2-pyridylmethyl)ethylamine, cis-fac-Ru(bpea)22+, and its homologue attached covalently to a polypyrrole film

New ruthenium complexes bearing tridentate ligands of general formula cis-fac-[(RuL2)-L-II][PF6](2) (L=N,N-bis(2-pyridylmethyl)ethylamine (bpea) 1 or N-[3-bis(2-pyridylmethyl)aminopropyl]pyrrole (bpea-pyr) 2) have been prepared following two different synthetic routes. They have been characterised by elemental analyses, UV-Vis and H-1 NMR spectroscopy. Furthermore, the crystal structure of complex 1 has been solved. The Ru is co-ordinated in a distorted octahedral fashion by six N atoms of two bpea ligands which occupy opposite faces of the octahedron. The aliphatic N atoms of the bpea ligands are co-ordinated in a cis fashion. 1-D together with 2-D NMR spectra show that in solution 1 has the same structure as in the solid state and that complex 2 has the same structural arrangement. The redox properties of 1 and 2 have been investigated by cyclic voltammetry and coulometry. In the anodic region, the pyrrole group of complex 2 polymerises forming a modified electrode containing Pt/poly-2. This new material has been characterised by electrochemical techniques and displays a remarkable chemical and electrochemical stability.