Pyrophosphate complexes isomers

Heterocyclic compounds have in most cases been hydroxylated by modified forms of Fenton s reagent. For instance, EDTA or pyrophosphate have been added to the system to complex the ferrous ions. It has been shown in the reactions of bcnzenoid compounds, however, that addition of complexing agents does not affect the distribution of isomers obtained by Fenton s reagent,and therefore the hydroxyl radical must still be the hydroxylating species. 

The syntheses and uses of these and other analogous complexes is reviewed elsewhere (15-17). The complex A Co(III)(NH3)4ATP is a substrate for hexoki-nase, whereas the A isomer is not, which suggests that the bidentate complex A MgATP is the natural substrate (19). The complex A Co(III)(NH3)4ATP is a substrate for phosphoribosyl pyrophosphate synthetase (20). The results of many similar studies are compiled in the review by Eckstein (21). 

Electron-diffraction measurements on trimethyl phosphate are best interpreted by assuming the presence of two rotational isomers the molecular parameters reported are cf(P=0) 1.477 cf(P—O) 1.580 d 0—C) 1.432 A, Z.OPO 105.2°, and Z.POC 118.4°. Thermal condensation reactions between trialkyl phosphates and dialkyl phosphorochloridates give monophosphorus side-products in addition to alkyl pyrophosphates. Detailed examinations of such systems suggest that oxonium-type intermediates such as (111) are involved rather than quasi-phosphonium complexes. 

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