Applications of tripodal [S₃] and [Se₃] L₂X donor ligands to zinc, cadmium and mercury chemistry: organometallic and bioinorganic perspectives

The tripodal tris(2-mercapto-1-R–imidazolyl)hydroborato ligand system, [Tm^R], and its selenium counterpart, [Tse^R], provide useful platforms for investigating organometallic and bioinorganic aspects of the chemistry of zinc, cadmium and mercury in sulfur-rich and selenium-rich coordination environments. For example, the tridentate [Tm^R] ligand provides an [S₃] donor array that is of use for mimicking aspects of zinc enzymes and proteins that have sulfur-rich active sites, such as the Ada DNA repair protein. With respect to mercury, an interesting application of the [Tm^But] ligand is the synthesis of the mercury alkyl compounds [Tm^But]HgR (R = Me, Et) that react with PhSH to yield [Tm^But]HgSPh and RH, a reaction that emulates mercury detoxification by the organomercurial lyase, MerB. In addition to the tridentate [Tm^R] and [Tse^R] ligands, applications of the bidentate counterparts, [Bm^R] and [Bse^R] are also described.