Assembly of a New Family of Mercury(II) Zwitterionic Thiolate Complexes from a Preformed Compound [Hg(Tab)2](PF6)2 [Tab = 4-(Trimethylammonio)benzenethiolate

Abstract

Reactions of Hg(OAc)2 with 2 equiv of TabHPF6 [TabH = 4-(trimethylammonio)benzenethiol] in MeCN/MeOH afforded a mononuclear linear complex [Hg(Tab)2](PF6)2 (1). By using 1 as a precursor, a new family of mercury(II) zwitterionic thiolate complexes, [Hg2(Tab)6](PF6)4.2MeCN (2.2MeCN), [Hg(Tab)2(SCN)](PF6) (3), [Hg(Tab)2(SCN)2] (4), [Hg(Tab)I2] (5), {[Hg(Tab)2]4[HgI2][Hg2I6]}(PF6)2(NO3)4 (6), [Hg(Tab)2][HgI4] (7), [Hg(Tab)2][HgCl2(SCN)2] (8), [Tab-Tab]2[Hg3Cl10] (9), and [Hg2(Tab)6]3(PF6)Cl11 (10), were prepared and characterized by elemental analysis, IR spectra, UV-vis spectra, 1H NMR, and single-crystal X-ray crystallography. The [Hg2(Tab)6]4+ tetracation of 2 or 10 contains an asymmetrical Hg2S2 rhomb with an inversion center lying on the midpoint of the Hg...Hg line. The Hg atom of the [Hg(Tab)2]2+ dication of 3 is coordinated to one SCN-, forming a rare T-shaped coordination geometry, while in 4, the Hg atom of [Hg(Tab)2]2+ is coordinated to two SCN-, forming a seesaw-shaped coordination geometry. Through weak secondary Hg...S coordinations, each cation in 3 is further linked to afford a one-dimensional zigzag chain. The trigonal [Hg(Tab)I2] molecules in 5 are held together by weak secondary Hg...I and Hg...S interactions, forming a one-dimensional chain structure. In 6, the four [Hg(Tab)2]2+ dications, one HgI2 molecule, one [Hg2I6]2- dianion, one PF6-, and four NO3- anions are interconnected by complicated secondary Hg...I and Hg...O interactions, forming a scolopendra-like chain structure. The secondary Hg...I interactions, [Hg(Tab)2]2+ and [HgI4]2- in 7, are combined to generate a one-dimensional chain structure, while [Hg(Tab)2]2+ and [HgCl2(SCN)2]2- in 8 are interconnected by secondary Hg...N interactions to form a one-dimensional zigzag chain structure. Compound 9 consists of two [Tab-Tab]2+ dications and one [Hg3Cl10]4- tetraanion. The facile approach to the construction of 2-8 and 10 from 1 may be applicable to the mimicking of a coordination sphere of the Hg sites of metallothioneins.