Na2MnCoNiO6 crystallizes in the monoclinic Cm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(1), one O(4), two equivalent O(2), and two equivalent O(5) atoms. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to one O(1), one O(4), two equivalent O(3), and two equivalent O(6) atoms. Mn(1) is bonded to one O(1), one O(4), two equivalent O(3), and two equivalent O(5) atoms to form MnO6 octahedra that share edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. Co(1) is bonded to one O(3), one O(6), two equivalent O(2), and two equivalent O(4) atoms to form CoO6 octahedra that share edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. Ni(1) is bonded to one O(2), one O(5), two equivalent O(1), and two equivalent O(6) atoms to form NiO6 octahedra that share edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), one Mn(1), and two equivalent Ni(1) atoms to form distorted ONa2MnNi2 trigonal bipyramids that share corners with four equivalent O(6)Na2CoNi2 square pyramids,  a cornercorner with one O(4)Na2MnCo2 trigonal bipyramid, corners with two equivalent O(5)Na2Mn2Ni trigonal bipyramids, corners with two equivalent O(1)Na2MnNi2 trigonal bipyramids,  an edgeedge with one O(6)Na2CoNi2 square pyramid, edges with two equivalent O(2)Na2Co2Ni square pyramids,  an edgeedge with one O(4)Na2MnCo2 trigonal bipyramid, edges with two equivalent O(3)Na2Mn2Co trigonal bipyramids, and edges with two equivalent O(5)Na2Mn2Ni trigonal bipyramids. In the second O site, O(2) is bonded to two equivalent Na(1), two equivalent Co(1), and one Ni(1) atom to form ONa2Co2Ni square pyramids that share corners with two equivalent O(3)Na2Mn2Co trigonal bipyramids, corners with three equivalent O(5)Na2Mn2Ni trigonal bipyramids, corners with four equivalent O(4)Na2MnCo2 trigonal bipyramids, edges with two equivalent O(2)Na2Co2Ni square pyramids, edges with two equivalent O(6)Na2CoNi2 square pyramids,  an edgeedge with one O(5)Na2Mn2Ni trigonal bipyramid,  an edgeedge with one O(4)Na2MnCo2 trigonal bipyramid, and edges with two equivalent O(1)Na2MnNi2 trigonal bipyramids. In the third O site, O(3) is bonded to two equivalent Na(2), two equivalent Mn(1), and one Co(1) atom to form distorted ONa2Mn2Co trigonal bipyramids that share corners with two equivalent O(2)Na2Co2Ni square pyramids, corners with three equivalent O(6)Na2CoNi2 square pyramids, corners with two equivalent O(5)Na2Mn2Ni trigonal bipyramids, corners with two equivalent O(4)Na2MnCo2 trigonal bipyramids,  an edgeedge with one O(6)Na2CoNi2 square pyramid,  an edgeedge with one O(5)Na2Mn2Ni trigonal bipyramid, edges with two equivalent O(3)Na2Mn2Co trigonal bipyramids, edges with two equivalent O(4)Na2MnCo2 trigonal bipyramids, and edges with two equivalent O(1)Na2MnNi2 trigonal bipyramids. In the fourth O site, O(4) is bonded to one Na(1), one Na(2), one Mn(1), and two equivalent Co(1) atoms to form distorted ONa2MnCo2 trigonal bipyramids that share corners with four equivalent O(2)Na2Co2Ni square pyramids,  a cornercorner with one O(1)Na2MnNi2 trigonal bipyramid, corners with two equivalent O(3)Na2Mn2Co trigonal bipyramids, corners with two equivalent O(4)Na2MnCo2 trigonal bipyramids,  an edgeedge with one O(2)Na2Co2Ni square pyramid, edges with two equivalent O(6)Na2CoNi2 square pyramids,  an edgeedge with one O(1)Na2MnNi2 trigonal bipyramid, edges with two equivalent O(3)Na2Mn2Co trigonal bipyramids, and edges with two equivalent O(5)Na2Mn2Ni trigonal bipyramids. In the fifth O site, O(5) is bonded to two equivalent Na(1), two equivalent Mn(1), and one Ni(1) atom to form distorted ONa2Mn2Ni trigonal bipyramids that share corners with two equivalent O(6)Na2CoNi2 square pyramids, corners with three equivalent O(2)Na2Co2Ni square pyramids, corners with two equivalent O(3)Na2Mn2Co trigonal bipyramids, corners with two equivalent O(1)Na2MnNi2 trigonal bipyramids,  an edgeedge with one O(2)Na2Co2Ni square pyramid,  an edgeedge with one O(3)Na2Mn2Co trigonal bipyramid, edges with two equivalent O(5)Na2Mn2Ni trigonal bipyramids, edges with two equivalent O(4)Na2MnCo2 trigonal bipyramids, and edges with two equivalent O(1)Na2MnNi2 trigonal bipyramids. In the sixth O site, O(6) is bonded to two equivalent Na(2), one Co(1), and two equivalent Ni(1) atoms to form ONa2CoNi2 square pyramids that share corners with two equivalent O(5)Na2Mn2Ni trigonal bipyramids, corners with three equivalent O(3)Na2Mn2Co trigonal bipyramids, corners with four equivalent O(1)Na2MnNi2 trigonal bipyramids, edges with two equivalent O(2)Na2Co2Ni square pyramids, edges with two equivalent O(6)Na2CoNi2 square pyramids,  an edgeedge with one O(3)Na2Mn2Co trigonal bipyramid,  an edgeedge with one O(1)Na2MnNi2 trigonal bipyramid, and edges with two equivalent O(4)Na2MnCo2 trigonal bipyramids.
Na2MnCoNiO6 crystallizes in the monoclinic Cm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(1), one O(4), two equivalent O(2), and two equivalent O(5) atoms. The Na(1)-O(1) bond length is 2.56 Å. The Na(1)-O(4) bond length is 2.55 Å. Both Na(1)-O(2) bond lengths are 2.32 Å. Both Na(1)-O(5) bond lengths are 2.43 Å. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to one O(1), one O(4), two equivalent O(3), and two equivalent O(6) atoms. The Na(2)-O(1) bond length is 2.62 Å. The Na(2)-O(4) bond length is 2.57 Å. Both Na(2)-O(3) bond lengths are 2.43 Å. Both Na(2)-O(6) bond lengths are 2.36 Å. Mn(1) is bonded to one O(1), one O(4), two equivalent O(3), and two equivalent O(5) atoms to form MnO6 octahedra that share edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. The Mn(1)-O(1) bond length is 1.95 Å. The Mn(1)-O(4) bond length is 1.93 Å. Both Mn(1)-O(3) bond lengths are 1.96 Å. Both Mn(1)-O(5) bond lengths are 1.94 Å. Co(1) is bonded to one O(3), one O(6), two equivalent O(2), and two equivalent O(4) atoms to form CoO6 octahedra that share edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. The Co(1)-O(3) bond length is 2.12 Å. The Co(1)-O(6) bond length is 2.04 Å. Both Co(1)-O(2) bond lengths are 1.95 Å. Both Co(1)-O(4) bond lengths are 2.03 Å. Ni(1) is bonded to one O(2), one O(5), two equivalent O(1), and two equivalent O(6) atoms to form NiO6 octahedra that share edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. The Ni(1)-O(2) bond length is 2.12 Å. The Ni(1)-O(5) bond length is 2.13 Å. Both Ni(1)-O(1) bond lengths are 1.97 Å. Both Ni(1)-O(6) bond lengths are 1.95 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Na(2), one Mn(1), and two equivalent Ni(1) atoms to form distorted ONa2MnNi2 trigonal bipyramids that share corners with four equivalent O(6)Na2CoNi2 square pyramids,  a cornercorner with one O(4)Na2MnCo2 trigonal bipyramid, corners with two equivalent O(5)Na2Mn2Ni trigonal bipyramids, corners with two equivalent O(1)Na2MnNi2 trigonal bipyramids,  an edgeedge with one O(6)Na2CoNi2 square pyramid, edges with two equivalent O(2)Na2Co2Ni square pyramids,  an edgeedge with one O(4)Na2MnCo2 trigonal bipyramid, edges with two equivalent O(3)Na2Mn2Co trigonal bipyramids, and edges with two equivalent O(5)Na2Mn2Ni trigonal bipyramids. In the second O site, O(2) is bonded to two equivalent Na(1), two equivalent Co(1), and one Ni(1) atom to form ONa2Co2Ni square pyramids that share corners with two equivalent O(3)Na2Mn2Co trigonal bipyramids, corners with three equivalent O(5)Na2Mn2Ni trigonal bipyramids, corners with four equivalent O(4)Na2MnCo2 trigonal bipyramids, edges with two equivalent O(2)Na2Co2Ni square pyramids, edges with two equivalent O(6)Na2CoNi2 square pyramids,  an edgeedge with one O(5)Na2Mn2Ni trigonal bipyramid,  an edgeedge with one O(4)Na2MnCo2 trigonal bipyramid, and edges with two equivalent O(1)Na2MnNi2 trigonal bipyramids. In the third O site, O(3) is bonded to two equivalent Na(2), two equivalent Mn(1), and one Co(1) atom to form distorted ONa2Mn2Co trigonal bipyramids that share corners with two equivalent O(2)Na2Co2Ni square pyramids, corners with three equivalent O(6)Na2CoNi2 square pyramids, corners with two equivalent O(5)Na2Mn2Ni trigonal bipyramids, corners with two equivalent O(4)Na2MnCo2 trigonal bipyramids,  an edgeedge with one O(6)Na2CoNi2 square pyramid,  an edgeedge with one O(5)Na2Mn2Ni trigonal bipyramid, edges with two equivalent O(3)Na2Mn2Co trigonal bipyramids, edges with two equivalent O(4)Na2MnCo2 trigonal bipyramids, and edges with two equivalent O(1)Na2MnNi2 trigonal bipyramids. In the fourth O site, O(4) is bonded to one Na(1), one Na(2), one Mn(1), and two equivalent Co(1) atoms to form distorted ONa2MnCo2 trigonal bipyramids that share corners with four equivalent O(2)Na2Co2Ni square pyramids,  a cornercorner with one O(1)Na2MnNi2 trigonal bipyramid, corners with two equivalent O(3)Na2Mn2Co trigonal bipyramids, corners with two equivalent O(4)Na2MnCo2 trigonal bipyramids,  an edgeedge with one O(2)Na2Co2Ni square pyramid, edges with two equivalent O(6)Na2CoNi2 square pyramids,  an edgeedge with one O(1)Na2MnNi2 trigonal bipyramid, edges with two equivalent O(3)Na2Mn2Co trigonal bipyramids, and edges with two equivalent O(5)Na2Mn2Ni trigonal bipyramids. In the fifth O site, O(5) is bonded to two equivalent Na(1), two equivalent Mn(1), and one Ni(1) atom to form distorted ONa2Mn2Ni trigonal bipyramids that share corners with two equivalent O(6)Na2CoNi2 square pyramids, corners with three equivalent O(2)Na2Co2Ni square pyramids, corners with two equivalent O(3)Na2Mn2Co trigonal bipyramids, corners with two equivalent O(1)Na2MnNi2 trigonal bipyramids,  an edgeedge with one O(2)Na2Co2Ni square pyramid,  an edgeedge with one O(3)Na2Mn2Co trigonal bipyramid, edges with two equivalent O(5)Na2Mn2Ni trigonal bipyramids, edges with two equivalent O(4)Na2MnCo2 trigonal bipyramids, and edges with two equivalent O(1)Na2MnNi2 trigonal bipyramids. In the sixth O site, O(6) is bonded to two equivalent Na(2), one Co(1), and two equivalent Ni(1) atoms to form ONa2CoNi2 square pyramids that share corners with two equivalent O(5)Na2Mn2Ni trigonal bipyramids, corners with three equivalent O(3)Na2Mn2Co trigonal bipyramids, corners with four equivalent O(1)Na2MnNi2 trigonal bipyramids, edges with two equivalent O(2)Na2Co2Ni square pyramids, edges with two equivalent O(6)Na2CoNi2 square pyramids,  an edgeedge with one O(3)Na2Mn2Co trigonal bipyramid,  an edgeedge with one O(1)Na2MnNi2 trigonal bipyramid, and edges with two equivalent O(4)Na2MnCo2 trigonal bipyramids.