Metal Complexes of Amino Acids. XII. The Deuteration of α-Hydrogen Atoms in Cobalt(III) Complexes Containing α-Amino Carboxylates

Abstract
The second-order rate constants (rate=kD(base)[Complex][OD−]) for the deuterium exchange of α-methylene or α-methine protons in the amino carboxylato complexes, trans(O)-, C1-cis(O)-, and C2-cis(O)-[Co(gly)2(en)]+ and -[Co(gly)2(tn)]+, [Co(gly)(NH3)4]2+, [Co(gly)(en)2]2+, [Co(gly)(tn)2]2+, [Co(sar)(en)2]2+, and Λ- and Δ-[Co(l-ala)(en)2]2+, were determined by the 1H-NMR measurement. The major factors determining the deuteration rate of α-hydrogens in the amino carboxylate chelate are the geometry and charge of the complex, and the nature of the substituent bonded to the chelate ring to be deuterated; the minor factor is the chelate-ring size of the ligands other than amino carboxylate in a complex molecule.
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