Effect of Metallation on C—H Exchange

The exchange on uracil and cytosine complexes has also been noted [44], and the formation of substituted uracil from the CI2 oxidation of Pt(II)—uracil complexes to Pt(IV) also reflects the increased reactivity 

The activation of the Cg-H bond upon metallation is really a mimic of the Mo-catalyzed enzyme xanthine oxidase which catalyzes the oxidation of xanthine to uric acid [46]  

Studies on the reactivity of the [Ru(NH3)5(Guo)] cation showed that one of the decomposition products, upon metal ion induced hydrolysis of the sugar—purine bond, was 8-hydroxyguanine, indicating oxidation of the bound ligand [47]. The propensity for Ru(III) to bind to this carbon (Cg) site, when no nitrogen ligands are available, has been demonstrated also in the caffeine and 4,5-dimethylimidazole complexes of [Ru(NH3)5] where the presence of a Ru—C bond has been structurally confirmed [48,49]. 

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