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

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.

合成了带有分子内NH···S氢键的单核Zn、Cd、Hg 1,2-苯二硫醇盐类配合物，其通式为[MII{1,2-S2-3,6-(RCONH)2C6H2}2]2−（其中R为CH3、叔丁基(t-Bu)，M为Zn、Cd、Hg），并通过X射线分析（X-ray analysis）与光谱测量对其完成了表征。通过红外光谱（IR spectra）证实了分子内NH···S氢键的存在。199Hg与113Cd核磁共振（nuclear magnetic resonance）分析结果表明，该类配合物为稳定的四硫醇盐配位结构，并提示NH···S氢键对pπ(Hg)−pπ(S)相互作用存在影响。NH伸缩振动峰显示，Cd与Hg配合物中的NH···S氢键强度高于对应Zn配合物中的氢键。上述结果得到了理论计算的支持。实验与理论结果均表明，NH···S氢键可影响金属硫蛋白（metallothioneins）对有毒Cd和Hg离子的高效捕获。