Na2ZnSe2 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 3-coordinate geometry to one Se(1) and two equivalent Se(2) atoms. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to four equivalent Se(2) atoms. Zn(1) is bonded to one Se(2) and three equivalent Se(1) atoms to form a mixture of distorted edge and corner-sharing ZnSe4 tetrahedra. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 4-coordinate geometry to one Na(1) and three equivalent Zn(1) atoms. In the second Se site, Se(2) is bonded to two equivalent Na(1), four equivalent Na(2), and one Zn(1) atom to form a mixture of distorted edge and corner-sharing SeNa6Zn pentagonal bipyramids.
Na2ZnSe2 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 3-coordinate geometry to one Se(1) and two equivalent Se(2) atoms. The Na(1)-Se(1) bond length is 2.91 Å. There is one shorter (2.91 Å) and one longer (2.96 Å) Na(1)-Se(2) bond length. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to four equivalent Se(2) atoms. There are a spread of Na(2)-Se(2) bond distances ranging from 2.90-2.97 Å. Zn(1) is bonded to one Se(2) and three equivalent Se(1) atoms to form a mixture of distorted edge and corner-sharing ZnSe4 tetrahedra. The Zn(1)-Se(2) bond length is 2.39 Å. There are a spread of Zn(1)-Se(1) bond distances ranging from 2.47-2.53 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 4-coordinate geometry to one Na(1) and three equivalent Zn(1) atoms. In the second Se site, Se(2) is bonded to two equivalent Na(1), four equivalent Na(2), and one Zn(1) atom to form a mixture of distorted edge and corner-sharing SeNa6Zn pentagonal bipyramids.