Group 17 elements mercury complexes

Literally hundreds of complex equilibria like this can be combined to model what happens to metals in aqueous systems. Numerous speciation models exist for this application that include all of the necessary equilibrium constants. Several of these models include surface complexation reactions that take place at the particle-water interface. Unlike the partitioning of hydrophobic organic contaminants into organic carbon, metals actually form ionic and covalent bonds with surface ligands such as sulfhydryl groups on metal sulfides and oxide groups on the hydrous oxides of manganese and iron. Metals also can be biotransformed to more toxic species (e.g., conversion of elemental mercury to methyl-mercury by anaerobic bacteria), less toxic species (oxidation of tributyl tin to elemental tin), or temporarily immobilized (e.g., via microbial reduction of sulfate to sulfide, which then precipitates as an insoluble metal sulfide mineral). 

NaK29Hg48 A Complex Ternary Amalgam With Mercury Acting as a Pseudo Group 13 Element [9]... 

Zinc, cadmium and mercury are at the end of the transition series and have electron configurations ndw(n + l)s2 with filled d shells. They do not form any compound in which the d shell is other than full (unlike the metals Cu, Ag and Au of the preceding group) these metals therefore do not show the variable valence which is one of the characteristics of the transition metals. In this respect these metals are regarded as non-transition elements. They show, however, some resemblance to the d-metals for instance in their ability to form complexes (with NH3, amines, cyanide, halide ions, etc.). 

The elements of this group (zinc Zn, cadmium Cd, mercury Hg) all exhibit a II oxidation state in aqueous systems, and Hg also shows a I oxidation state as indicated by the unusual cation Hg2. None of the elements shows oxidation states greater than II, which indicates that the d electrons are not involved. Within the group Zn and Cd resemble each other more closely than Cd and Hg. This is especially evident in the nobility of Hg (E° positive for Zn and Cd, negative for Hg), the lack of an Hg hydroxide, the thermal instability of HgO, and the greater stabilities of many Hg complexes as compared to those of Zn and Cd. 

A number of comparative studies have been made of organogold compounds and related complexes of neighboring metals, notably platinum and mercury as well as the other group IB elements. These comparisons have included such aspects of their chemistry as thermal stability and reactivity, bonding modes, and spectroscopic data. 

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