A ZINC(II) COMPLEX OF VITAMIN B1

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Abstract
The importance of divalent metal ions in the catalytic efficiency of the enzyme pyruvate decarboxylase is well documented.1- Although Zn2+ is not the most effective of all the divalent metal ions, it is definitely important in this catalytic efficiency trend. All the metal thiamine complexes reported4–7 thus far have proved the two major points that metal-thiamine complexes do actually exist and that the binding site is the N(1′) position of the pyrimidine group of thiamine in agreement with Schellenberger′s proposal.8 Recently7, we reported the preparation, proton and carbon-13 NMR data of a new Cd2+ thiamine complex, Cd(thiamine)Cl3, which was the first NMR report on a metal-thiamine complex whose structure had been previously determined by X-ray crystallographic methods.5 In view of our continuing interest in metal-thiamine complexes, we report the preparation, infrared, proton and carbon-13 NMR studies of a new zinc(II)-thiamine complex, Zn(thiamine)Cl3. We compare the proton and carbon-13 NMR data of Zn(thiamine)Cl3 and Cd(thiamine)Cl3.