DOE OSTI2020
HfHg4(AsCl3)2 crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. Hf4+ is bonded in an octahedral geometry to six Cl1- atoms. There are a spread of Hf–Cl bond distances ranging from 2.46–2.51 Å. There are four inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded in a 3-coordinate geometry to two As3- and one Cl1- atom. There are one shorter (2.52 Å) and one longer (2.53 Å) Hg–As bond lengths. The Hg–Cl bond length is 3.40 Å. In the second Hg2+ site, Hg2+ is bonded in a 4-coordinate geometry to two As3- and two Cl1- atoms. There are one shorter (2.51 Å) and one longer (2.52 Å) Hg–As bond lengths. There are one shorter (3.37 Å) and one longer (3.47 Å) Hg–Cl bond lengths. In the third Hg2+ site, Hg2+ is bonded in a distorted rectangular see-saw-like geometry to two As3- and two Cl1- atoms. Both Hg–As bond lengths are 2.54 Å. There are one shorter (3.07 Å) and one longer (3.32 Å) Hg–Cl bond lengths. In the fourth Hg2+ site, Hg2+ is bonded in a 6-coordinate geometry to two As3- and four Cl1- atoms. There are one shorter (2.54 Å) and one longer (2.55 Å) Hg–As bond lengths. There are a spread of Hg–Cl bond distances ranging from 3.23–3.52 Å. There are two inequivalent As3- sites. In the first As3- site, As3- is bonded to four Hg2+ atoms to form corner-sharing AsHg4 tetrahedra. In the second As3- site, As3- is bonded to four Hg2+ atoms to form corner-sharing AsHg4 tetrahedra. There are six inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one Hf4+ and two equivalent Hg2+ atoms. In the second Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one Hf4+ and two Hg2+ atoms. In the third Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one Hf4+ and one Hg2+ atom. In the fourth Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one Hf4+ and two Hg2+ atoms. In the fifth Cl1- site, Cl1- is bonded in a single-bond geometry to one Hf4+ and one Hg2+ atom. In the sixth Cl1- site, Cl1- is bonded in a distorted bent 120 degrees geometry to one Hf4+ and one Hg2+ atom.