1. Investigating Copper-Thiophene Binding Interactions: Impact on the Desulfurization of Hydrocarbon Fuels by Adsorption Processes
John T. York, Department of Chemistry, Stetson University
The binding of organic thiophene and benzothiophenes to copper(I) centers is proposed to play an important role in adsorption processes that utilize copper salts to bind to and remove sulfur-containing impurities from petroleum fuels. We are using both density functional theory and synthetic chemistry to help elucidate the fundamental nature of bonding in organometallic copper-thiophene complexes.
Utilizing 2,2’-bipyridine (bipy) as a prototypical supporting ligand, DFT calculations were performed to predict the geometries and stabilities of potential [LCuI(thiophene)]+ adducts. Calculations predict the h2-thiophene adduct to be preferred over the h1-thiophene geometry.
Donor
Orbitals
Cu 3d
thiophene p
More Stable
Less Stable
A detailed bonding analysis of the [(bipy)CuI(h2-thiophene)]+ adduct reveals that the bonding interactions are consistent with the traditional Dewar-Chatt-Duncanson model: they consist primarily of p-backbonding from a filled Cu 3d orbital into an empty p* orbital of the thiophene, and s-donation from a filled p-orbital of the thiophene into the Cu 4s orbital. This bonding picture is similar to that calculated for the simple alkene ethylene.
thiophene p*
Cu 4s
Acceptor
Orbitals