Materials Data on NaHf8(NCl)8 by Materials Project

Abstract

NaHf8(NCl)8 crystallizes in the monoclinic P2/m space group. The structure is two-dimensional and consists of one NaHf8(NCl)8 sheet oriented in the (0, 0, 1) direction. Na is bonded to six Cl atoms to form edge-sharing NaCl6 octahedra. There are four shorter (2.75 Å) and two longer (2.77 Å) Na–Cl bond lengths. There are four inequivalent Hf sites. In the first Hf site, Hf is bonded in a 7-coordinate geometry to four N and three Cl atoms. There are three shorter (2.13 Å) and one longer (2.19 Å) Hf–N bond lengths. There are one shorter (2.75 Å) and two longer (2.77 Å) Hf–Cl bond lengths. In the second Hf site, Hf is bonded in a 7-coordinate geometry to four N and three Cl atoms. There are three shorter (2.13 Å) and one longer (2.19 Å) Hf–N bond lengths. There are one shorter (2.75 Å) and two longer (2.78 Å) Hf–Cl bond lengths. In the third Hf site, Hf is bonded in a 4-coordinate geometry to four N and three Cl atoms. There are one shorter (2.10 Å) and three longer (2.11 Å) Hf–N bond lengths. There are one shorter (2.85 Å) and two longer (2.92 Å) Hf–Cl bond lengths. In the fourth Hf site, Hf is bonded in a 4-coordinate geometry to four N and three Cl atoms. There are one shorter (2.11 Å) and three longer (2.12 Å) Hf–N bond lengths. There are two shorter (2.87 Å) and one longer (2.88 Å) Hf–Cl bond lengths. There are four inequivalent N sites. In the first N site, N is bonded to four Hf atoms to form NHf4 trigonal pyramids that share corners with three equivalent ClNa2Hf3 square pyramids, corners with six NHf4 trigonal pyramids, an edgeedge with one ClNa2Hf3 square pyramid, and edges with three NHf4 tetrahedra. In the second N site, N is bonded to four Hf atoms to form NHf4 trigonal pyramids that share corners with six NHf4 trigonal pyramids, edges with two equivalent ClNa2Hf3 square pyramids, and edges with three NHf4 tetrahedra. In the third N site, N is bonded to four Hf atoms to form NHf4 tetrahedra that share corners with two equivalent ClNa2Hf3 square pyramids, corners with six NHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. In the fourth N site, N is bonded to four Hf atoms to form NHf4 tetrahedra that share a cornercorner with one ClNa2Hf3 square pyramid, corners with six NHf4 tetrahedra, and edges with three NHf4 trigonal pyramids. There are four inequivalent Cl sites. In the first Cl site, Cl is bonded to two equivalent Na and three Hf atoms to form distorted ClNa2Hf3 square pyramids that share corners with two equivalent ClNa2Hf3 square pyramids, corners with three NHf4 tetrahedra, corners with three equivalent NHf4 trigonal pyramids, edges with three equivalent ClNa2Hf3 square pyramids, and edges with three NHf4 trigonal pyramids. In the second Cl site, Cl is bonded in a distorted see-saw-like geometry to one Na and three Hf atoms. In the third Cl site, Cl is bonded in a 3-coordinate geometry to three Hf atoms. In the fourth Cl site, Cl is bonded in a 3-coordinate geometry to three Hf atoms.