Formation of an Unusual Pseudo-Square Planar-Induced Mercury(II) Dimeric Complex

Due to the different crystallization methods, two Hg(II) complexes of a 19-membered NO2S2-macrocycle (L) and its oxidized ligand (HLox), exhibiting different stoichiometries, were prepared. First, mercury(II) iodide reacts with L to afford a dinuclear metallacycle complex [Hg-2(L)(2)I-4] (1) in which the mercury(II) exists outside the macrocyclic cavity. Meanwhile, the slow diffusion reaction gave an unusual pseudo-square planar-induced mercury(II) complex, which shows three separated parts with the formula [Hg-2(HLox)I-5](2)[HgI2] (2). There are two complex cation units that are exo-coordinated, along with one unit consisting of a metal cluster anion. Surprisingly, L was oxidized in the disulfoxidized form (HLox) in this condition. NMR titration was used to monitor both the structural and binding characteristics of the complex formed between L and mercury(II) iodide in a solution.