Materials Data on Na(Cu2Sb)2 by Materials Project
NaCu4Sb2 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Na1+ is bonded to six equivalent Sb3- atoms to form edge-sharing NaSb6 octahedra. All Na–Sb bond lengths are 3.26 Å. There are two inequivalent Cu+1.25+ sites. In the first Cu+1.25+ site, Cu+1.25+ is bonded in a 1-coordinate geometry to three equivalent Cu+1.25+ and four equivalent Sb3- atoms. All Cu–Cu bond lengths are 2.56 Å. There are one shorter (2.70 Å) and three longer (2.88 Å) Cu–Sb bond lengths. In the second Cu+1.25+ site, Cu+1.25+ is bonded in a trigonal non-coplanar geometry to three equivalent Cu+1.25+ and three equivalent Sb3- atoms. All Cu–Sb bond lengths are 2.60 Å. Sb3- is bonded in a 10-coordinate geometry to three equivalent Na1+ and seven Cu+1.25+ atoms.