“That’s Not Coming Off of There”; An Exploration of Ligand Lability in Carbon Tetrachloride Dechlorination Technologies

Abstract

Carbon Tetrachloride (CT) is a carcinogenic industrial solvent, and known environmental contaminant. The Department of Energy’s Hanford Site has been identified as a Superfund Site. CT, is just one of the many environmental concerns. Environmentally CT dechlorinates in a stepwise manner forming lesser chlorinated intermediate complexes that pose a health threat to humans. [Cu(PDTC)L] is a small coordination compound capable of dechlorinating CT into less harmless decomposition products: CO2 and Cl-. In this study we draw a correlation between the dechlorination kinetics of CT of [Cu(PDTC)L] and the ligand liability of the L ligand. We use P K-edge X-Ray Absorption Spectroscopy to quanititate the phosphorus covalency of a series of PR3 transition metal ligands [Cu(PDTC)L] (L= PPh3, and PCy3). Our results show that there is no correlation between the covalent character of Cu-P bonds and the kinetics of dechlorination.Instead, we propose that the correlation has a greater correlation with the solubility of a ligand in a given solvent system.