The [Cu(tmen)(OH)(OH2)]+ promoted hydrolysis of 2,4-dinitrophenyl diethyl phosphate and O-isopropyl methylphosphonofluoridate (sarin) (tmen = N,N,N′N′-tetramethyl-1,2-diaminoethane)

The hydrolysis of the phosphate triester 2,4-dinitrophenyl diethyl phosphate to diethyl phosphate is catalysed by [Cu(tmen)(OH)(OH2)](+) in the pH range 6.5 to 8.0. At pH 7 with a catalyst concentration of 2.5 x 10(-3) mol dm(-3) the rate enhancement is ca 10(4) fold. The pH dependence of the catalysis is consistent with the hydroxoaqua complex being the active species in the hydrolysis. The greater kinetic effectiveness of this weak base, compared with hydroxide ion on a molar basis, indicates a bifunctional mechanism in which bound hydroxide acts as a nucleophile in conjunction with electrophilic catalysis by copper at the phosphoryl oxygen. The copper complex is an excellent catalyst for the hydrolysis of O-isopropyl methylphosphonofluoridate (Sarin). At pH 7 and 25 degrees C using a Sarin concentration of 4.5 x 10(-2) mol dm(-3) and a [Cu(tmen)(OH2)(2)](2+) concentration of 5 x 10(-3) mol dm(-3), complete hydrolysis (9 turnovers) occurs in 13 min. (C) 1998 Elsevier Science Ltd. All rights reserved.