Scott N. Goldie, PhD - WSU Research Experience

I worked as an undergraduate in the laboratory of Prof. David B. Rorabacher from 1993 to 1995 at Wayne State University. Initially, I determined the equilibrium constant for the conproportionation of Cu ^I in 80% methanol using a stopped-flow spectrophotometric determination method that I developed. From these data, the first formal potential value for the Cu^(II/I) couple in 80% methanol was determined. These data were then used in the determination of stability constants of Cu^II([14]-aneS₄) (1,4,8,11-tetrathiacyclotetradecane) and several of its derivatives in acetonitrile and were compared to the stability constants for these complexes in aqueous solution. This work resulted in a contribution to a publication in the ACS journal Inorganic Chemistry ("Effect of Ligand Constraints upon the Stabilities and Potentials of Macrocyclic Polythiaether Complexes. Copper^II and Copper^I Complexes with Cyclohexyl and Phenyl Derivatives of [14]aneS₄ in Water, 80% Methanol, and Acetonitrile", Inorg. Chem. 1995, 34, 357) and a presentation at the International Symposium on Macrocyclic Chemistry in Lawrence, Kansas. ("Introduction of Conformational Constraints in the [14]aneS₄ Macrocycle: Effects on Copper (II/I) Complex Stabilities and Potentials in Water, 80% Methanol, and Acetonitrile", XIX International Symposium on Macrocyclic Chemistry, Lawrence, KS. June, 1994.)

The studies lead to a determination of the stability constants of a series of the same cis/trans substituted [14]aneS₄ based ligands and Ni^II in acetonitrile through the use of the McConnell-Davidson spectrophotometric measurement technique. I used a Cary UV/Visible spectrograph and wet chemistry techniques to make the first quantitative report of stability constants for other metal ions besides Cu^II with a series of polythiaether ligands. It was determined that Cu^II is about 106 times more selective than Ni^II in these ligands, which is a much higher difference than has been observed for any other class of ligands.

Simultaneously, I was the first to determine complex formation rate constants for reactions of solvated Ni^II with eight macrocyclic tetrathiaether ligands in acetonitrile, using stopped flow instrumentation and ultraviolet/visible absorption spectroscopy. These data, when coupled with the independently determined dissociation rate constants, allowed for a comparison to similar metal/ligand systems in acetonitrile and N, N-dimethylformamide (DMF) to study the applicability of the Eigen-Wilkens mechanism to these systems and determine the validity of the mechanistic interpretation to these macrocyclic ligand/metal systems.

As an undergraduate, Dr. Rorabacher encouraged me to participate in undergraduate research symposium and forums. This result in two presentations, "Thermodynamic and Formation Kinetic Studies of Nickel (II) and Tetrathiaether Macrocycles in Acetonitrile", Wayne State University American Chemical Society Undergraduate Research Symposium, Detroit, MI. April, 1995 and "Thermodynamic and Formation Kinetic Studies of Nickel (II) and Tetrathiaether Macrocycles in Acetonitrile", Great Lakes College Chemistry Conference, Michigan State University, East Lansing, MI. March, 1995.

After graduation in May, 1995, this work was completed by Chandrika P. Kulatilleke, a graduate student in the Rorabacher group, and then was published in Inorganic Chemistry "Formation and Dissociation Kinetics of Nickel (II)-Macrocyclic Tetrathiaether Complexes in Acetonitrile - Comparison to the Kinetics of Macrocyclic Tetramines" Inorg. Chem., 2000, 39 (7), 1444. and "Unusually High Selectivity of Polythiaethers for Copper (II) over Nickel (II)" Inorg. Chem., 1999, 38 (25), 5906.