DOE OSTI2020
Na2Ti3Cl8 is beta indium sulfide-derived structured and crystallizes in the trigonal R3m space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six Cl1- atoms to form distorted NaCl6 pentagonal pyramids that share corners with six equivalent TiCl6 octahedra, edges with three equivalent TiCl6 octahedra, and edges with three equivalent NaCl6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 37°. There are three shorter (2.78 Å) and three longer (2.83 Å) Na–Cl bond lengths. In the second Na1+ site, Na1+ is bonded to six Cl1- atoms to form distorted NaCl6 pentagonal pyramids that share corners with six equivalent TiCl6 octahedra, edges with three equivalent TiCl6 octahedra, and edges with three equivalent NaCl6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 54°. There are three shorter (2.75 Å) and three longer (2.85 Å) Na–Cl bond lengths. Ti2+ is bonded to six Cl1- atoms to form distorted TiCl6 octahedra that share corners with four NaCl6 pentagonal pyramids, edges with four equivalent TiCl6 octahedra, and edges with two NaCl6 pentagonal pyramids. There are a spread of Ti–Cl bond distances ranging from 2.39–2.69 Å. There are four inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded to two Na1+ and two equivalent Ti2+ atoms to form a mixture of edge and corner-sharing ClNa2Ti2 trigonal pyramids. In the second Cl1- site, Cl1- is bonded in a rectangular see-saw-like geometry to two Na1+ and two equivalent Ti2+ atoms. In the third Cl1- site, Cl1- is bonded in a 3-coordinate geometry to three equivalent Ti2+ atoms. In the fourth Cl1- site, Cl1- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Ti2+ atoms.