urbach_300pxEmeritus Professor of Chemistry


216.368.3668      flu@case.edu      Millis 225D

Interests: Analytical Chemistry, Biochemistry, Inorganic Chemistry, Bio-Inorganic Chemistry, Catalysis

BS, Pennsylvania State University, 1960
PhD, Michigan State University, 1964
Postdoctoral Associate, Ohio State University, 1964-66
Fulbright Lecturer, Colombia, 1976
Visiting Professor, Institute for Inorganic Chemistry, Basel, Switzerland, 1976


Transition Metal Complexes with Redox Active Ligands

The redox capacity of a transitionmetal ion can be expanded by comlexing the metal ion with a redox active ligand. Metal complexes of this type exhibit multi-electron transfers which are the sum of the oxidation state changes in the metal center plus redox changes in the ligand. The enhanced redox capacity of these complexes yields the possiblity that they may act as “electron reservoirs” and/or may facilitate multi-electron redox catalysis such as dioxygen reduction. Complexes with redox active ligands may also mimic the interactions between transition metal ions and organic-based redox centers in biological systems.

Professor Urbach’s group has designed and synthesized an extensive variety of new binuclear transition metal chelates containing redox active ligands and has characterized them by UV-VIS spectroscopy, magnetic susceptibility measurements, and electron paramagnetic resonance. Since these studies focus on the ability of metal chelates to undergo multi-electron transfers, complete electrochemical characterization of their redox behavior has been carried out by cyclic, rotating disk, and square wave voltammetries, controlled potential electrolysis and spectroelectrochemistry.

Two types of metal complexes are currently under investigation: dicopper complexes containing binucleating ligands derived from 1,4-hydroquinone, and cobalt porphyrins which contain catechol substituents at the meso bridging positions. The dicopper complexes are an outgrowth of prior studies on biomimetic copper complexes. The cobalt porphyrins are under investigation as improved electrocatalysts for dioxygen reduction for potential applications in fuel cells.

Selected Publications
  • “Dicopper(II) Complexes with Flexible Binucleating Ligands Containing Two Tridentate Coordination Sites” Polyhedron 2001, 20, 541-549.
  • “Dinuclear copper(II) complexes incorporating a novel pyrazolo-based ligand with S- and N-rich coordination spheres” Polyhedron 2000, 19, 2215-2223.
  • “Alkali Metal Induced Rupture of a Phosphorus-Phosphorus Double Bond. Electrochemical and EPR Investigations of New Sterically Protected Diphosphenes and Radical Anions [ArPPAr]-” Organometallics 1997, 16, 3395-3400. (With J. D. Protasiewicz)
  • “In Situ Vanadium K-Edge and Tungsten LIII-Edge X-Ray Absorption Fine Structure of Vanadium-Substituted Heteropolytungstates Immobilized in a high-Area Carbon Electrode in Acid Aqueou Electrolytes” Journal of Physical Chemistry 1996, 100, 18511-18514. (With D. A. Scherson)