DOE OSTI2020
W2Hg2O7 crystallizes in the monoclinic C2/c space group. The structure is two-dimensional and consists of two W2Hg2O7 sheets oriented in the (0, 0, 1) direction. there are two inequivalent W5+ sites. In the first W5+ site, W5+ is bonded to six O2- atoms to form a mixture of distorted corner and edge-sharing WO6 octahedra. The corner-sharing octahedra tilt angles range from 11–31°. There are a spread of W–O bond distances ranging from 1.77–2.26 Å. In the second W5+ site, W5+ is bonded to six O2- atoms to form a mixture of distorted corner and edge-sharing WO6 octahedra. The corner-sharing octahedra tilt angles range from 15–31°. There are a spread of W–O bond distances ranging from 1.77–2.24 Å. There are two inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded in a 1-coordinate geometry to one O2- atom. The Hg–O bond length is 2.20 Å. In the second Hg2+ site, Hg2+ is bonded in a 1-coordinate geometry to two O2- atoms. There are one shorter (2.17 Å) and one longer (2.98 Å) Hg–O bond lengths. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one W5+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two W5+ and two Hg2+ atoms. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to two W5+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two W5+ and one Hg2+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to one W5+ atom. In the sixth O2- site, O2- is bonded in a distorted linear geometry to two W5+ atoms. In the seventh O2- site, O2- is bonded in a linear geometry to two equivalent W5+ atoms. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent W5+ atoms.