Hg(II)⋅d [M] Interactions: Are they Metallophilic Interactions or Spodium Bonds?

Some literature reports have shown the existence of short Hg(II)⋅⋅⋅d [M] (M=Pd, Pt) contacts between linear Hg(II) and square planar d [M] complexes that have been defined as heterometallophilic interactions. Linear L-Hg(II)-L complexes exhibit a π-hole or positive belt of electrostatic potential at the Hg atom, whereas late transition metals can serve as effective electron donors through their filled d 2 orbitals. This study provides compelling evidence that Hg(II)⋅⋅⋅d [M] interactions should be more appropriately termed spodium bonds.