Hydrolysis of Phosphate Esters and Related Reactions

The fine balance between available mechanisms is seen in the hydrolysis of the related complex [Co(NH3)5(03POAr)]+, which also occurs by an SNlcb mechanism, with attack on the co-ordinated phosphate by co-ordinated amide. A similar mechanism involving 

4 Other Reactions of Co-ordinated Ligands with Nucleophiles 

Very rapid hydrolyses of phosphate esters and polyphosphates are observed in the presence of labile metal ions such as copper(n), calcium(n) or magnesium(n) (Fig. 4-50). 

Reactions involving the formation and hydrolysis of phosphate and polyphosphate esters are of vital importance in biological systems in which it is found that magnesium ions are almost invariably implicated. The formation and decomposition of adenosine triphosphate are the fundamental reactions involved in energy storage in living systems. In this context, it is perhaps relevant to note that the hydrolysis of ATP is enhanced, albeit in a very modest manner, by some cobalt(m) complexes. 

It is found that the hydrolysis of fluorophosphate esters is also accelerated by transition metal ions and complexes. This would be an observation of little general interest, except for the fact that fluorophosphate esters form one of the more commonly encountered types of nerve gases (Fig. 4-51). The hydrolysis of fluorophosphate esters is increased dramatically in the presence of copper(n) and other transition metal complexes, and this sug- 

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