The hydrolysis of cyclic adenosine 3′,5′-monophosphate and 2′-deoxythymidylyl(3′-5′)2′-deoxythymidine by Ce(NH 4)2(NO3)6 was kinetically studied. The rate of hydrolysis was fairly proportional to the concentration of [Ce 2IV (OH)4]4+, showing that this is the catalytically active species. According to quantum-chemical calculation, the two Ce(IV) ions in this [Ce2IV (OH)4] 4+ cluster are bridged by two OH residues. Upon the complex formation with H2PO4- (a model compound for the phosphodiesters), these two Ce(IV) ions bind the two oxygen atoms of the substrate and enhance the electrophilicity of the phosphorus atom. The catalytic mechanism of Ce(IV)-induced hydrolysis of phosphodiesters has been proposed on the basis these results.
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