Applications of tripodal [S-3] and [Se-3] 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 [S-3] 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.