K2Na2IrO4 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 5-coordinate geometry to one O(2), two equivalent O(1), and two equivalent O(4) atoms. In the second K site, K(2) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(4), and two equivalent O(2) atoms. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), and two equivalent O(3) atoms. In the second Na site, Na(2) is bonded to one O(1), one O(2), one O(4), and two equivalent O(3) atoms to form edge-sharing NaO5 trigonal bipyramids. Ir(1) is bonded in a rectangular see-saw-like geometry to one O(1), one O(2), one O(3), and one O(4) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one K(2), two equivalent K(1), one Na(1), one Na(2), and one Ir(1) atom. In the second O site, O(2) is bonded to one K(1), two equivalent K(2), one Na(1), one Na(2), and one Ir(1) atom to form distorted OK3Na2Ir octahedra that share corners with two equivalent O(2)K3Na2Ir octahedra, corners with four equivalent O(3)KNa4Ir octahedra, edges with two equivalent O(4)K3Na2Ir octahedra,  a faceface with one O(4)K3Na2Ir octahedra, and  a faceface with one O(3)KNa4Ir octahedra. The corner-sharing octahedral tilt angles range from 3-64°. In the third O site, O(3) is bonded to one K(2), two equivalent Na(1), two equivalent Na(2), and one Ir(1) atom to form distorted OKNa4Ir octahedra that share corners with four equivalent O(2)K3Na2Ir octahedra, corners with four equivalent O(4)K3Na2Ir octahedra,  an edgeedge with one O(4)K3Na2Ir octahedra, edges with two equivalent O(3)KNa4Ir octahedra, and  a faceface with one O(2)K3Na2Ir octahedra. The corner-sharing octahedral tilt angles range from 3-60°. In the fourth O site, O(4) is bonded to one K(2), two equivalent K(1), one Na(1), one Na(2), and one Ir(1) atom to form distorted OK3Na2Ir octahedra that share corners with two equivalent O(4)K3Na2Ir octahedra, corners with four equivalent O(3)KNa4Ir octahedra,  an edgeedge with one O(3)KNa4Ir octahedra, edges with two equivalent O(2)K3Na2Ir octahedra, and  a faceface with one O(2)K3Na2Ir octahedra. The corner-sharing octahedral tilt angles range from 16-60°.
K2Na2IrO4 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 5-coordinate geometry to one O(2), two equivalent O(1), and two equivalent O(4) atoms. The K(1)-O(2) bond length is 2.73 Å. There is one shorter (2.74 Å) and one longer (2.79 Å) K(1)-O(1) bond length. There is one shorter (2.69 Å) and one longer (2.78 Å) K(1)-O(4) bond length. In the second K site, K(2) is bonded in a 5-coordinate geometry to one O(1), one O(3), one O(4), and two equivalent O(2) atoms. The K(2)-O(1) bond length is 2.97 Å. The K(2)-O(3) bond length is 2.89 Å. The K(2)-O(4) bond length is 2.81 Å. There is one shorter (2.75 Å) and one longer (2.84 Å) K(2)-O(2) bond length. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), and two equivalent O(3) atoms. The Na(1)-O(1) bond length is 2.38 Å. The Na(1)-O(2) bond length is 2.44 Å. The Na(1)-O(4) bond length is 2.31 Å. There is one shorter (2.36 Å) and one longer (2.46 Å) Na(1)-O(3) bond length. In the second Na site, Na(2) is bonded to one O(1), one O(2), one O(4), and two equivalent O(3) atoms to form edge-sharing NaO5 trigonal bipyramids. The Na(2)-O(1) bond length is 2.40 Å. The Na(2)-O(2) bond length is 2.40 Å. The Na(2)-O(4) bond length is 2.33 Å. There is one shorter (2.35 Å) and one longer (2.45 Å) Na(2)-O(3) bond length. Ir(1) is bonded in a rectangular see-saw-like geometry to one O(1), one O(2), one O(3), and one O(4) atom. The Ir(1)-O(1) bond length is 1.94 Å. The Ir(1)-O(2) bond length is 1.93 Å. The Ir(1)-O(3) bond length is 1.95 Å. The Ir(1)-O(4) bond length is 1.94 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one K(2), two equivalent K(1), one Na(1), one Na(2), and one Ir(1) atom. In the second O site, O(2) is bonded to one K(1), two equivalent K(2), one Na(1), one Na(2), and one Ir(1) atom to form distorted OK3Na2Ir octahedra that share corners with two equivalent O(2)K3Na2Ir octahedra, corners with four equivalent O(3)KNa4Ir octahedra, edges with two equivalent O(4)K3Na2Ir octahedra,  a faceface with one O(4)K3Na2Ir octahedra, and  a faceface with one O(3)KNa4Ir octahedra. The corner-sharing octahedral tilt angles range from 3-64°. In the third O site, O(3) is bonded to one K(2), two equivalent Na(1), two equivalent Na(2), and one Ir(1) atom to form distorted OKNa4Ir octahedra that share corners with four equivalent O(2)K3Na2Ir octahedra, corners with four equivalent O(4)K3Na2Ir octahedra,  an edgeedge with one O(4)K3Na2Ir octahedra, edges with two equivalent O(3)KNa4Ir octahedra, and  a faceface with one O(2)K3Na2Ir octahedra. The corner-sharing octahedral tilt angles range from 3-60°. In the fourth O site, O(4) is bonded to one K(2), two equivalent K(1), one Na(1), one Na(2), and one Ir(1) atom to form distorted OK3Na2Ir octahedra that share corners with two equivalent O(4)K3Na2Ir octahedra, corners with four equivalent O(3)KNa4Ir octahedra,  an edgeedge with one O(3)KNa4Ir octahedra, edges with two equivalent O(2)K3Na2Ir octahedra, and  a faceface with one O(2)K3Na2Ir octahedra. The corner-sharing octahedral tilt angles range from 16-60°.