Ab initio calculations on P-C bond cleavage in phosphoranyl radicals: Implications for the biodegradation of organophosphonate derivatives

Barrier heights for P-C bond homolysis in P-hydroxy-P-methyl-P,P-dioxophosphoranyl and P,P,P-trihydroxy-P-methylphosphoranyl were calculated using well correlated levels of electronic structure theory. The best estimate for the difference in barriers between the two indicates that homolysis is more facile for P,P,P-trihydroxy-P-methylphosphoranyl by roughly 9 kcal mol^-1. This result suggests that bacterial pathways leading to P-C bond cleavage in organophosphonate derivatives will preferentially proceed via initial one-electron reduction of substrates rather than oxidation.