Mercury polycations

[8] The presence of Hg2+2 units in the solid state was first determined in 1926 using X-ray diffraction.

[3] Most salts with main group elements tend to contain only Hg(II) and metallic mercury, because the presence of strong Lewis bases destabilizes the intermetallic bond.

In appropriate solvents, however, Hg(I) salts with derivatives of amides, pyridines, phosphorus trifluoride, tin(II), and certain other main group elements are all known.

[3] The triangular Hg4+3 cation was confirmed in a reinvestigation of the mineral terlinguaite in 1989[4] and subsequently synthesised in a number of compounds.

[12] The golden yellow compound Hg2.86(AsF6), named "alchemists' gold" by its discoverers,[5] contains perpendicular chains of Hg atoms.