Materials Data on KNa2(NiO2)2 by Materials Project
KNa2(NiO2)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. K1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of K–O bond distances ranging from 2.64–3.07 Å. There are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to five O2- atoms to form distorted edge-sharing NaO5 trigonal bipyramids. There are two shorter (2.39 Å) and three longer (2.41 Å) Na–O bond lengths. In the second Na1+ site, Na1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Na–O bond distances ranging from 2.37–2.52 Å. There are two inequivalent Ni+2.50+ sites. In the first Ni+2.50+ site, Ni+2.50+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Ni–O bond distances ranging from 1.96–2.00 Å. In the second Ni+2.50+ site, Ni+2.50+ is bonded in a square co-planar geometry to four O2- atoms. There are a spread of Ni–O bond distances ranging from 1.81–1.89 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to one K1+, three Na1+, and two Ni+2.50+ atoms. In the second O2- site, O2- is bonded in a 6-coordinate geometry to one K1+, three Na1+, and two Ni+2.50+ atoms. In the third O2- site, O2- is bonded in a 6-coordinate geometry to two equivalent K1+, two Na1+, and two Ni+2.50+ atoms. In the fourth O2- site, O2- is bonded in a 6-coordinate geometry to two equivalent K1+, two Na1+, and two Ni+2.50+ atoms.