NaMg6CrO8 is Caswellsilverite-derived structured and crystallizes in the tetragonal P4/mmm space group. Na(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form NaO6 octahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with four equivalent Na(1)O6 octahedra, edges with four equivalent Mg(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with four equivalent Mg(1)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. In the second Mg site, Mg(2) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Mg(2)O6 octahedra, edges with four equivalent Cr(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. In the third Mg site, Mg(3) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form MgO6 octahedra that share corners with six equivalent Mg(3)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with two equivalent Cr(1)O6 octahedra, and edges with four equivalent Mg(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-16°. Cr(1) is bonded to two equivalent O(1) and four equivalent O(4) atoms to form CrO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with four equivalent Cr(1)O6 octahedra, edges with four equivalent Mg(2)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), four equivalent Mg(3), and one Cr(1) atom to form ONaMg4Cr octahedra that share corners with six equivalent O(1)NaMg4Cr octahedra, edges with four equivalent O(4)Mg4Cr2 octahedra, edges with four equivalent O(2)Mg6 octahedra, and edges with four equivalent O(3)Na2Mg4 octahedra. The corner-sharing octahedral tilt angles range from 0-16°. In the second O site, O(2) is bonded to one Mg(1), one Mg(2), and four equivalent Mg(3) atoms to form OMg6 octahedra that share corners with six equivalent O(2)Mg6 octahedra, edges with four equivalent O(4)Mg4Cr2 octahedra, edges with four equivalent O(3)Na2Mg4 octahedra, and edges with four equivalent O(1)NaMg4Cr octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the third O site, O(3) is bonded to two equivalent Na(1), two equivalent Mg(1), and two equivalent Mg(3) atoms to form ONa2Mg4 octahedra that share corners with two equivalent O(4)Mg4Cr2 octahedra, corners with four equivalent O(3)Na2Mg4 octahedra, edges with four equivalent O(2)Mg6 octahedra, edges with four equivalent O(3)Na2Mg4 octahedra, and edges with four equivalent O(1)NaMg4Cr octahedra. The corner-sharing octahedra are not tilted. In the fourth O site, O(4) is bonded to two equivalent Mg(2), two equivalent Mg(3), and two equivalent Cr(1) atoms to form OMg4Cr2 octahedra that share corners with two equivalent O(3)Na2Mg4 octahedra, corners with four equivalent O(4)Mg4Cr2 octahedra, edges with four equivalent O(4)Mg4Cr2 octahedra, edges with four equivalent O(2)Mg6 octahedra, and edges with four equivalent O(1)NaMg4Cr octahedra. The corner-sharing octahedra are not tilted.
NaMg6CrO8 is Caswellsilverite-derived structured and crystallizes in the tetragonal P4/mmm space group. Na(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form NaO6 octahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with four equivalent Na(1)O6 octahedra, edges with four equivalent Mg(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. Both Na(1)-O(1) bond lengths are 2.35 Å. All Na(1)-O(3) bond lengths are 2.14 Å. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form MgO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with four equivalent Mg(1)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. Both Mg(1)-O(2) bond lengths are 2.20 Å. All Mg(1)-O(3) bond lengths are 2.14 Å. In the second Mg site, Mg(2) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Mg(2)O6 octahedra, edges with four equivalent Cr(1)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. Both Mg(2)-O(2) bond lengths are 2.12 Å. All Mg(2)-O(4) bond lengths are 2.14 Å. In the third Mg site, Mg(3) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form MgO6 octahedra that share corners with six equivalent Mg(3)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, edges with two equivalent Cr(1)O6 octahedra, and edges with four equivalent Mg(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-16°. The Mg(3)-O(3) bond length is 2.05 Å. The Mg(3)-O(4) bond length is 2.26 Å. Both Mg(3)-O(1) bond lengths are 2.16 Å. Both Mg(3)-O(2) bond lengths are 2.15 Å. Cr(1) is bonded to two equivalent O(1) and four equivalent O(4) atoms to form CrO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with four equivalent Cr(1)O6 octahedra, edges with four equivalent Mg(2)O6 octahedra, and edges with eight equivalent Mg(3)O6 octahedra. The corner-sharing octahedra are not tilted. Both Cr(1)-O(1) bond lengths are 1.96 Å. All Cr(1)-O(4) bond lengths are 2.14 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), four equivalent Mg(3), and one Cr(1) atom to form ONaMg4Cr octahedra that share corners with six equivalent O(1)NaMg4Cr octahedra, edges with four equivalent O(4)Mg4Cr2 octahedra, edges with four equivalent O(2)Mg6 octahedra, and edges with four equivalent O(3)Na2Mg4 octahedra. The corner-sharing octahedral tilt angles range from 0-16°. In the second O site, O(2) is bonded to one Mg(1), one Mg(2), and four equivalent Mg(3) atoms to form OMg6 octahedra that share corners with six equivalent O(2)Mg6 octahedra, edges with four equivalent O(4)Mg4Cr2 octahedra, edges with four equivalent O(3)Na2Mg4 octahedra, and edges with four equivalent O(1)NaMg4Cr octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the third O site, O(3) is bonded to two equivalent Na(1), two equivalent Mg(1), and two equivalent Mg(3) atoms to form ONa2Mg4 octahedra that share corners with two equivalent O(4)Mg4Cr2 octahedra, corners with four equivalent O(3)Na2Mg4 octahedra, edges with four equivalent O(2)Mg6 octahedra, edges with four equivalent O(3)Na2Mg4 octahedra, and edges with four equivalent O(1)NaMg4Cr octahedra. The corner-sharing octahedra are not tilted. In the fourth O site, O(4) is bonded to two equivalent Mg(2), two equivalent Mg(3), and two equivalent Cr(1) atoms to form OMg4Cr2 octahedra that share corners with two equivalent O(3)Na2Mg4 octahedra, corners with four equivalent O(4)Mg4Cr2 octahedra, edges with four equivalent O(4)Mg4Cr2 octahedra, edges with four equivalent O(2)Mg6 octahedra, and edges with four equivalent O(1)NaMg4Cr octahedra. The corner-sharing octahedra are not tilted.