CUII DIAMINE COMPLEX-CATALYZED HYDROLYSIS OF PHOSPHATE TRIESTERS ADSORBED ON STRONG-BASE ION-EXCHANGE RESINS - P-31 NMR RELAXATION MEASUREMENTS

The Cu(II)-diamine complexes, (bipy)CuSO4 and (tmen)CuSO4, catalyze the hydrolysis of p-nitrophenyl diphenyl phosphate (PNDP) adsorbed on a strong-base ion exchange resin. Turnover is observed. The major hydrolysis products are diphenyl phosphate, p-nitrophenyl phenyl phosphate, and the ethanolysis product ethyl diphenyl phosphate (EDPP) which are observed in similar amounts in both the presence and absence of the Cu(II)-diamine catalysts. The apparent bimolecular rate constants found for the (bipy) CuSO4 and (tmen)CuSO4 catalysts are 0.023 and 0.024 M-1 s-1, respectively. CuSO4 is inactive as a catalyst. P-31 MAS NMR relaxation measurements of the stable EDPP product reveal that the Cu(II)-diamine complexes greatly enhance T1 relaxation, whereas CuSO4 has only minimal effect. These results are consistent with the complexation of neutral phosphorus esters by the Cu(II-diamine catalysts. P-31 T1 mesurements of hydrolytically-stable dimethyl methylphosphonate (DMMP) in water solutions of Cu2+, (tmen)Cu2+, and Mn2+ suggest that DMMP exchanges rapidly between inner-sphere and outer-sphere complexes in a nearly identical manner with each of these paramagnetic species.