A density functional role of ligand on the associated with ATRP theory computational study of the stability of CuI and CuII species and SET-LRP

Atom transfer radical polymerization (ATRP) and single electron-transfer living radical polymerization (SET-LRP) both utilize copper complexes of various oxidation states with N-ligands to perform their respective activation and deactivation steps. Herein, we utilize DFT (B3YLP) methods to determine the preferred ligand-binding geometries for Cu/N-ligand complexes related to ATRP and SET-LRP. We find that those ligands capable of achieving tetrahedral complexes with Cu-I and trigonal bipyramidal with axial halide complexes with [(CuX)-X-II](+) have higher energies of stabilization. We were able to correlate calculated preferential stabilization of [(CuX)-X-II](+) with those ligands that perform best in SET-LRR A crude calculation of energy of disproportionation revealed that the same preferential binding of [(CuX)-X-II]=+ results in increased propensity for disproportionation. Finally, by examining the relative energies of the basic steps of ATRP and SET-LRP, we were able to rationalize the transition from the ATRP mechanism to the SET-LRP mechanism as we transition from typical nonpolar ATRP solvents to polar SET-LRP solvents. (c) 2007 Wiley Periodicals, Inc.