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Zinc, Cadmium, and Mercury 1,2-Benzenedithiolates with Intramolecular NH···S Hydrogen Bonds

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journal contribution
posted on 07.04.2008, 00:00 by Koji Baba, Taka-aki Okamura, Hitoshi Yamamoto, Tetsuo Yamamoto, Norikazu Ueyama
Mononuclear Zn, Cd, and Hg 1,2-benzenedithiolates with intramolecular NH···S hydrogen bonds, [MII{1,2-S2-3,6-(RCONH)2C6H2}2]2− (R = CH3, t-Bu; M = Zn, Cd, Hg), were synthesized and characterized by X-ray analysis and spectral measurements. The presence of intramolecular NH···S hydrogen bonds was established by the IR spectra. 199Hg and 113Cd nuclear magnetic resonance showed a stabilized four-thiolate coordinated structure and suggested the influence of the NH···S hydrogen bonds to pπ(Hg)−pπ(S) interactions. The NH stretching bands show that the NH···S hydrogen bonds in Cd and Hg complexes are stronger than those in the corresponding Zn complex. These results are supported by theoretical calculations. The experimental and theoretical results suggested that the NH···S hydrogen bond influences the efficient capture of toxic Cd and Hg ions by metallothioneins.