Mo5Fe3N8 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. There are three inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one N(2), one N(3), two equivalent N(1), and two equivalent N(4) atoms to form distorted MoN6 pentagonal pyramids that share corners with two equivalent Fe(1)N6 octahedra, corners with four equivalent Mo(3)N6 octahedra, corners with six equivalent Fe(2)N6 octahedra, edges with two equivalent Mo(1)N6 pentagonal pyramids, edges with four equivalent Mo(2)N6 pentagonal pyramids,  a faceface with one Fe(1)N6 octahedra, and  a faceface with one Fe(2)N6 octahedra. The corner-sharing octahedral tilt angles range from 45-46°. In the second Mo site, Mo(2) is bonded to one N(1), one N(4), two equivalent N(2), and two equivalent N(3) atoms to form distorted MoN6 pentagonal pyramids that share corners with two equivalent Mo(3)N6 octahedra, corners with four equivalent Fe(1)N6 octahedra, corners with six equivalent Fe(2)N6 octahedra, edges with two equivalent Mo(2)N6 pentagonal pyramids, edges with four equivalent Mo(1)N6 pentagonal pyramids,  a faceface with one Mo(3)N6 octahedra, and  a faceface with one Fe(2)N6 octahedra. The corner-sharing octahedral tilt angles range from 44-47°. In the third Mo site, Mo(3) is bonded to two equivalent N(1) and four equivalent N(2) atoms to form distorted MoN6 octahedra that share corners with four equivalent Mo(2)N6 pentagonal pyramids, corners with eight equivalent Mo(1)N6 pentagonal pyramids, edges with two equivalent Mo(3)N6 octahedra, edges with four equivalent Fe(1)N6 octahedra, and faces with two equivalent Mo(2)N6 pentagonal pyramids. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent N(2) and four equivalent N(1) atoms to form FeN6 octahedra that share corners with four equivalent Mo(1)N6 pentagonal pyramids, corners with eight equivalent Mo(2)N6 pentagonal pyramids, edges with two equivalent Fe(1)N6 octahedra, edges with four equivalent Mo(3)N6 octahedra, and faces with two equivalent Mo(1)N6 pentagonal pyramids. In the second Fe site, Fe(2) is bonded to three equivalent N(3) and three equivalent N(4) atoms to form FeN6 octahedra that share corners with six equivalent Mo(1)N6 pentagonal pyramids, corners with six equivalent Mo(2)N6 pentagonal pyramids, edges with six equivalent Fe(2)N6 octahedra,  a faceface with one Mo(1)N6 pentagonal pyramid, and  a faceface with one Mo(2)N6 pentagonal pyramid. There are four inequivalent N sites. In the first N site, N(1) is bonded to one Mo(2), one Mo(3), two equivalent Mo(1), and two equivalent Fe(1) atoms to form distorted NFe2Mo4 pentagonal pyramids that share corners with two equivalent N(4)Fe3Mo3 pentagonal pyramids, corners with three equivalent N(1)Fe2Mo4 pentagonal pyramids, corners with four equivalent N(3)Fe3Mo3 pentagonal pyramids, edges with three equivalent N(1)Fe2Mo4 pentagonal pyramids, edges with six equivalent N(2)FeMo5 pentagonal pyramids, and  a faceface with one N(4)Fe3Mo3 pentagonal pyramid. In the second N site, N(2) is bonded to one Mo(1), two equivalent Mo(2), two equivalent Mo(3), and one Fe(1) atom to form distorted NFeMo5 pentagonal pyramids that share corners with two equivalent N(3)Fe3Mo3 pentagonal pyramids, corners with three equivalent N(2)FeMo5 pentagonal pyramids, corners with four equivalent N(4)Fe3Mo3 pentagonal pyramids, edges with three equivalent N(2)FeMo5 pentagonal pyramids, edges with six equivalent N(1)Fe2Mo4 pentagonal pyramids, and  a faceface with one N(3)Fe3Mo3 pentagonal pyramid. In the third N site, N(3) is bonded to one Mo(1), two equivalent Mo(2), and three equivalent Fe(2) atoms to form distorted NFe3Mo3 pentagonal pyramids that share corners with two equivalent N(2)FeMo5 pentagonal pyramids, corners with three equivalent N(4)Fe3Mo3 pentagonal pyramids, corners with four equivalent N(1)Fe2Mo4 pentagonal pyramids, edges with four equivalent N(3)Fe3Mo3 pentagonal pyramids, edges with five equivalent N(4)Fe3Mo3 pentagonal pyramids, and  a faceface with one N(2)FeMo5 pentagonal pyramid. In the fourth N site, N(4) is bonded to one Mo(2), two equivalent Mo(1), and three equivalent Fe(2) atoms to form distorted NFe3Mo3 pentagonal pyramids that share corners with two equivalent N(1)Fe2Mo4 pentagonal pyramids, corners with three equivalent N(3)Fe3Mo3 pentagonal pyramids, corners with four equivalent N(2)FeMo5 pentagonal pyramids, edges with four equivalent N(4)Fe3Mo3 pentagonal pyramids, edges with five equivalent N(3)Fe3Mo3 pentagonal pyramids, and  a faceface with one N(1)Fe2Mo4 pentagonal pyramid.
Mo5Fe3N8 is Caswellsilverite-like structured and crystallizes in the monoclinic C2/m space group. There are three inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one N(2), one N(3), two equivalent N(1), and two equivalent N(4) atoms to form distorted MoN6 pentagonal pyramids that share corners with two equivalent Fe(1)N6 octahedra, corners with four equivalent Mo(3)N6 octahedra, corners with six equivalent Fe(2)N6 octahedra, edges with two equivalent Mo(1)N6 pentagonal pyramids, edges with four equivalent Mo(2)N6 pentagonal pyramids,  a faceface with one Fe(1)N6 octahedra, and  a faceface with one Fe(2)N6 octahedra. The corner-sharing octahedral tilt angles range from 45-46°. The Mo(1)-N(2) bond length is 2.14 Å. The Mo(1)-N(3) bond length is 2.15 Å. Both Mo(1)-N(1) bond lengths are 2.12 Å. Both Mo(1)-N(4) bond lengths are 2.14 Å. In the second Mo site, Mo(2) is bonded to one N(1), one N(4), two equivalent N(2), and two equivalent N(3) atoms to form distorted MoN6 pentagonal pyramids that share corners with two equivalent Mo(3)N6 octahedra, corners with four equivalent Fe(1)N6 octahedra, corners with six equivalent Fe(2)N6 octahedra, edges with two equivalent Mo(2)N6 pentagonal pyramids, edges with four equivalent Mo(1)N6 pentagonal pyramids,  a faceface with one Mo(3)N6 octahedra, and  a faceface with one Fe(2)N6 octahedra. The corner-sharing octahedral tilt angles range from 44-47°. The Mo(2)-N(1) bond length is 2.14 Å. The Mo(2)-N(4) bond length is 2.11 Å. Both Mo(2)-N(2) bond lengths are 2.14 Å. Both Mo(2)-N(3) bond lengths are 2.13 Å. In the third Mo site, Mo(3) is bonded to two equivalent N(1) and four equivalent N(2) atoms to form distorted MoN6 octahedra that share corners with four equivalent Mo(2)N6 pentagonal pyramids, corners with eight equivalent Mo(1)N6 pentagonal pyramids, edges with two equivalent Mo(3)N6 octahedra, edges with four equivalent Fe(1)N6 octahedra, and faces with two equivalent Mo(2)N6 pentagonal pyramids. Both Mo(3)-N(1) bond lengths are 2.18 Å. All Mo(3)-N(2) bond lengths are 2.21 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent N(2) and four equivalent N(1) atoms to form FeN6 octahedra that share corners with four equivalent Mo(1)N6 pentagonal pyramids, corners with eight equivalent Mo(2)N6 pentagonal pyramids, edges with two equivalent Fe(1)N6 octahedra, edges with four equivalent Mo(3)N6 octahedra, and faces with two equivalent Mo(1)N6 pentagonal pyramids. Both Fe(1)-N(2) bond lengths are 2.20 Å. All Fe(1)-N(1) bond lengths are 2.22 Å. In the second Fe site, Fe(2) is bonded to three equivalent N(3) and three equivalent N(4) atoms to form FeN6 octahedra that share corners with six equivalent Mo(1)N6 pentagonal pyramids, corners with six equivalent Mo(2)N6 pentagonal pyramids, edges with six equivalent Fe(2)N6 octahedra,  a faceface with one Mo(1)N6 pentagonal pyramid, and  a faceface with one Mo(2)N6 pentagonal pyramid. There are two shorter (2.11 Å) and one longer (2.12 Å) Fe(2)-N(3) bond length. There are two shorter (2.09 Å) and one longer (2.14 Å) Fe(2)-N(4) bond length. There are four inequivalent N sites. In the first N site, N(1) is bonded to one Mo(2), one Mo(3), two equivalent Mo(1), and two equivalent Fe(1) atoms to form distorted NFe2Mo4 pentagonal pyramids that share corners with two equivalent N(4)Fe3Mo3 pentagonal pyramids, corners with three equivalent N(1)Fe2Mo4 pentagonal pyramids, corners with four equivalent N(3)Fe3Mo3 pentagonal pyramids, edges with three equivalent N(1)Fe2Mo4 pentagonal pyramids, edges with six equivalent N(2)FeMo5 pentagonal pyramids, and  a faceface with one N(4)Fe3Mo3 pentagonal pyramid. In the second N site, N(2) is bonded to one Mo(1), two equivalent Mo(2), two equivalent Mo(3), and one Fe(1) atom to form distorted NFeMo5 pentagonal pyramids that share corners with two equivalent N(3)Fe3Mo3 pentagonal pyramids, corners with three equivalent N(2)FeMo5 pentagonal pyramids, corners with four equivalent N(4)Fe3Mo3 pentagonal pyramids, edges with three equivalent N(2)FeMo5 pentagonal pyramids, edges with six equivalent N(1)Fe2Mo4 pentagonal pyramids, and  a faceface with one N(3)Fe3Mo3 pentagonal pyramid. In the third N site, N(3) is bonded to one Mo(1), two equivalent Mo(2), and three equivalent Fe(2) atoms to form distorted NFe3Mo3 pentagonal pyramids that share corners with two equivalent N(2)FeMo5 pentagonal pyramids, corners with three equivalent N(4)Fe3Mo3 pentagonal pyramids, corners with four equivalent N(1)Fe2Mo4 pentagonal pyramids, edges with four equivalent N(3)Fe3Mo3 pentagonal pyramids, edges with five equivalent N(4)Fe3Mo3 pentagonal pyramids, and  a faceface with one N(2)FeMo5 pentagonal pyramid. In the fourth N site, N(4) is bonded to one Mo(2), two equivalent Mo(1), and three equivalent Fe(2) atoms to form distorted NFe3Mo3 pentagonal pyramids that share corners with two equivalent N(1)Fe2Mo4 pentagonal pyramids, corners with three equivalent N(3)Fe3Mo3 pentagonal pyramids, corners with four equivalent N(2)FeMo5 pentagonal pyramids, edges with four equivalent N(4)Fe3Mo3 pentagonal pyramids, edges with five equivalent N(3)Fe3Mo3 pentagonal pyramids, and  a faceface with one N(1)Fe2Mo4 pentagonal pyramid.