ThEr4CN4 is alpha Po-derived structured and crystallizes in the tetragonal I4/mmm space group. Th(1) is bonded to four equivalent C(1) and two equivalent N(1) atoms to form ThC4N2 octahedra that share corners with two equivalent Er(2)N6 octahedra, corners with four equivalent Th(1)C4N2 octahedra, edges with four equivalent Th(1)C4N2 octahedra, and edges with eight equivalent Er(1)CN5 octahedra. The corner-sharing octahedra are not tilted. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded to one C(1), one N(2), and four equivalent N(1) atoms to form ErCN5 octahedra that share  a cornercorner with one Er(2)N6 octahedra, corners with five equivalent Er(1)CN5 octahedra, edges with four equivalent Th(1)C4N2 octahedra, edges with four equivalent Er(1)CN5 octahedra, and edges with four equivalent Er(2)N6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. In the second Er site, Er(2) is bonded to one N(1) and five equivalent N(2) atoms to form ErN6 octahedra that share  a cornercorner with one Th(1)C4N2 octahedra,  a cornercorner with one Er(1)CN5 octahedra, corners with four equivalent Er(2)N6 octahedra, edges with four equivalent Er(1)CN5 octahedra, and edges with eight equivalent Er(2)N6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. C(1) is bonded to four equivalent Th(1) and two equivalent Er(1) atoms to form CEr2Th4 octahedra that share corners with two equivalent N(2)Er6 octahedra, corners with four equivalent C(1)Er2Th4 octahedra, edges with four equivalent C(1)Er2Th4 octahedra, and edges with eight equivalent N(1)Er5Th octahedra. The corner-sharing octahedra are not tilted. There are two inequivalent N sites. In the first N site, N(1) is bonded to one Th(1), one Er(2), and four equivalent Er(1) atoms to form NEr5Th octahedra that share  a cornercorner with one N(2)Er6 octahedra, corners with five equivalent N(1)Er5Th octahedra, edges with four equivalent C(1)Er2Th4 octahedra, edges with four equivalent N(1)Er5Th octahedra, and edges with four equivalent N(2)Er6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. In the second N site, N(2) is bonded to one Er(1) and five equivalent Er(2) atoms to form NEr6 octahedra that share  a cornercorner with one C(1)Er2Th4 octahedra,  a cornercorner with one N(1)Er5Th octahedra, corners with four equivalent N(2)Er6 octahedra, edges with four equivalent N(1)Er5Th octahedra, and edges with eight equivalent N(2)Er6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°.
ThEr4CN4 is alpha Po-derived structured and crystallizes in the tetragonal I4/mmm space group. Th(1) is bonded to four equivalent C(1) and two equivalent N(1) atoms to form ThC4N2 octahedra that share corners with two equivalent Er(2)N6 octahedra, corners with four equivalent Th(1)C4N2 octahedra, edges with four equivalent Th(1)C4N2 octahedra, and edges with eight equivalent Er(1)CN5 octahedra. The corner-sharing octahedra are not tilted. All Th(1)-C(1) bond lengths are 2.48 Å. Both Th(1)-N(1) bond lengths are 2.58 Å. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded to one C(1), one N(2), and four equivalent N(1) atoms to form ErCN5 octahedra that share  a cornercorner with one Er(2)N6 octahedra, corners with five equivalent Er(1)CN5 octahedra, edges with four equivalent Th(1)C4N2 octahedra, edges with four equivalent Er(1)CN5 octahedra, and edges with four equivalent Er(2)N6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. The Er(1)-C(1) bond length is 2.65 Å. The Er(1)-N(2) bond length is 2.35 Å. All Er(1)-N(1) bond lengths are 2.48 Å. In the second Er site, Er(2) is bonded to one N(1) and five equivalent N(2) atoms to form ErN6 octahedra that share  a cornercorner with one Th(1)C4N2 octahedra,  a cornercorner with one Er(1)CN5 octahedra, corners with four equivalent Er(2)N6 octahedra, edges with four equivalent Er(1)CN5 octahedra, and edges with eight equivalent Er(2)N6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. The Er(2)-N(1) bond length is 2.43 Å. There is one shorter (2.40 Å) and four longer (2.48 Å) Er(2)-N(2) bond lengths. C(1) is bonded to four equivalent Th(1) and two equivalent Er(1) atoms to form CEr2Th4 octahedra that share corners with two equivalent N(2)Er6 octahedra, corners with four equivalent C(1)Er2Th4 octahedra, edges with four equivalent C(1)Er2Th4 octahedra, and edges with eight equivalent N(1)Er5Th octahedra. The corner-sharing octahedra are not tilted. There are two inequivalent N sites. In the first N site, N(1) is bonded to one Th(1), one Er(2), and four equivalent Er(1) atoms to form NEr5Th octahedra that share  a cornercorner with one N(2)Er6 octahedra, corners with five equivalent N(1)Er5Th octahedra, edges with four equivalent C(1)Er2Th4 octahedra, edges with four equivalent N(1)Er5Th octahedra, and edges with four equivalent N(2)Er6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. In the second N site, N(2) is bonded to one Er(1) and five equivalent Er(2) atoms to form NEr6 octahedra that share  a cornercorner with one C(1)Er2Th4 octahedra,  a cornercorner with one N(1)Er5Th octahedra, corners with four equivalent N(2)Er6 octahedra, edges with four equivalent N(1)Er5Th octahedra, and edges with eight equivalent N(2)Er6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°.