Alchemists' Gold, Hg2.86 Asf6; An X-Ray Crystallographic Study of A Novel Disordered Mercury Compound Containing Metallically Bonded Infinite Cations

The compound Hg 2.86 AsF 6 belongs to the tetragonal space group I4 1 /amd with lattice parameters a = 7.538(4) Å, c = 12.339(5) Å, and Z = 4. The structure was refined using 109 symmetry independent reflections by full matrix least-squares refinement to a final R value of 0.079. The structure may be described as consisting of octahedral AsF 6 − ions arranged on a lattice which contains linear, non-intersecting channels in two mutually perpendicular directions. Within these channels are infinite chains of mercury atoms, each with a formal charge of +0.35, and with a mercury–mercury distance of 2.64(1) Å.