Metal ion effects in isotopic hydrogen exchange in biologically important heterocycles.
The binding of metal ions to heteroatomic centers of biomolecules has been utilized as a probe of metal ion effects in living systems. This article focuses on the effect of N-coordination by transition metals, especially Pt(II), Co(III), Cr(III), on isotopic C(2)-H or C(8)-H exchange of imidazoles, thiazoles, and purines. The usual reactivity trend, protonated >> metalated >> neutral substrate, is excepted for Cr(III)/1-methylimidazole, where Cr(III) activates stronger than H(+). An interplay of factors is considered, including metal-to-ligand back-bonding, electronic structure of metal ions, and differences in crystal field stabilization energy.
Buncel
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E
Department of Chemistry, Queen's University, Kingston, Canada K7L 3N6.
Clement
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O
Onyido
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I
D002412:Cations; D006571:Heterocyclic Compounds / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry; D007554:Isotopes; D007700:Kinetics; D008670:Metals / Q000737:chemistry*
D002412:Cations; D006571:Heterocyclic Compounds; D007554:Isotopes; D008670:Metals; D006859:Hydrogen