Nb3FeSe6 is Corundum-derived structured and crystallizes in the monoclinic C2 space group. There are four inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form distorted NbSe6 pentagonal pyramids that share corners with six equivalent Fe(1)Se6 octahedra and edges with six equivalent Nb(4)Se6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 46-47°. In the second Nb site, Nb(2) is bonded to two equivalent Se(4), two equivalent Se(5), and two equivalent Se(6) atoms to form distorted NbSe6 pentagonal pyramids that share corners with six equivalent Fe(1)Se6 octahedra and edges with six equivalent Nb(3)Se6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 46-47°. In the third Nb site, Nb(3) is bonded to two equivalent Se(4), two equivalent Se(5), and two equivalent Se(6) atoms to form distorted NbSe6 pentagonal pyramids that share corners with three equivalent Fe(1)Se6 octahedra, edges with three equivalent Nb(2)Se6 pentagonal pyramids, edges with three equivalent Nb(3)Se6 pentagonal pyramids, and  a faceface with one Fe(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 46-47°. In the fourth Nb site, Nb(4) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form distorted NbSe6 pentagonal pyramids that share corners with three equivalent Fe(1)Se6 octahedra, edges with three equivalent Nb(1)Se6 pentagonal pyramids, edges with three equivalent Nb(4)Se6 pentagonal pyramids, and  a faceface with one Fe(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 46-47°. Fe(1) is bonded to one Se(1), one Se(2), one Se(3), one Se(4), one Se(5), and one Se(6) atom to form FeSe6 octahedra that share corners with three equivalent Nb(1)Se6 pentagonal pyramids, corners with three equivalent Nb(2)Se6 pentagonal pyramids, corners with three equivalent Nb(3)Se6 pentagonal pyramids, corners with three equivalent Nb(4)Se6 pentagonal pyramids,  a faceface with one Nb(3)Se6 pentagonal pyramid, and  a faceface with one Nb(4)Se6 pentagonal pyramid. There are six inequivalent Se sites. In the first Se site, Se(1) is bonded in a rectangular see-saw-like geometry to one Nb(1), two equivalent Nb(4), and one Fe(1) atom. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to one Nb(1), two equivalent Nb(4), and one Fe(1) atom. In the third Se site, Se(3) is bonded in a rectangular see-saw-like geometry to one Nb(1), two equivalent Nb(4), and one Fe(1) atom. In the fourth Se site, Se(4) is bonded in a rectangular see-saw-like geometry to one Nb(2), two equivalent Nb(3), and one Fe(1) atom. In the fifth Se site, Se(5) is bonded in a rectangular see-saw-like geometry to one Nb(2), two equivalent Nb(3), and one Fe(1) atom. In the sixth Se site, Se(6) is bonded in a rectangular see-saw-like geometry to one Nb(2), two equivalent Nb(3), and one Fe(1) atom.
Nb3FeSe6 is Corundum-derived structured and crystallizes in the monoclinic C2 space group. There are four inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form distorted NbSe6 pentagonal pyramids that share corners with six equivalent Fe(1)Se6 octahedra and edges with six equivalent Nb(4)Se6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 46-47°. Both Nb(1)-Se(1) bond lengths are 2.62 Å. Both Nb(1)-Se(2) bond lengths are 2.61 Å. Both Nb(1)-Se(3) bond lengths are 2.61 Å. In the second Nb site, Nb(2) is bonded to two equivalent Se(4), two equivalent Se(5), and two equivalent Se(6) atoms to form distorted NbSe6 pentagonal pyramids that share corners with six equivalent Fe(1)Se6 octahedra and edges with six equivalent Nb(3)Se6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 46-47°. Both Nb(2)-Se(4) bond lengths are 2.61 Å. Both Nb(2)-Se(5) bond lengths are 2.61 Å. Both Nb(2)-Se(6) bond lengths are 2.61 Å. In the third Nb site, Nb(3) is bonded to two equivalent Se(4), two equivalent Se(5), and two equivalent Se(6) atoms to form distorted NbSe6 pentagonal pyramids that share corners with three equivalent Fe(1)Se6 octahedra, edges with three equivalent Nb(2)Se6 pentagonal pyramids, edges with three equivalent Nb(3)Se6 pentagonal pyramids, and  a faceface with one Fe(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 46-47°. There is one shorter (2.61 Å) and one longer (2.63 Å) Nb(3)-Se(4) bond length. There is one shorter (2.61 Å) and one longer (2.63 Å) Nb(3)-Se(5) bond length. There is one shorter (2.62 Å) and one longer (2.63 Å) Nb(3)-Se(6) bond length. In the fourth Nb site, Nb(4) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form distorted NbSe6 pentagonal pyramids that share corners with three equivalent Fe(1)Se6 octahedra, edges with three equivalent Nb(1)Se6 pentagonal pyramids, edges with three equivalent Nb(4)Se6 pentagonal pyramids, and  a faceface with one Fe(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 46-47°. There is one shorter (2.62 Å) and one longer (2.64 Å) Nb(4)-Se(1) bond length. There is one shorter (2.61 Å) and one longer (2.64 Å) Nb(4)-Se(2) bond length. There is one shorter (2.61 Å) and one longer (2.64 Å) Nb(4)-Se(3) bond length. Fe(1) is bonded to one Se(1), one Se(2), one Se(3), one Se(4), one Se(5), and one Se(6) atom to form FeSe6 octahedra that share corners with three equivalent Nb(1)Se6 pentagonal pyramids, corners with three equivalent Nb(2)Se6 pentagonal pyramids, corners with three equivalent Nb(3)Se6 pentagonal pyramids, corners with three equivalent Nb(4)Se6 pentagonal pyramids,  a faceface with one Nb(3)Se6 pentagonal pyramid, and  a faceface with one Nb(4)Se6 pentagonal pyramid. The Fe(1)-Se(1) bond length is 2.56 Å. The Fe(1)-Se(2) bond length is 2.57 Å. The Fe(1)-Se(3) bond length is 2.57 Å. The Fe(1)-Se(4) bond length is 2.57 Å. The Fe(1)-Se(5) bond length is 2.58 Å. The Fe(1)-Se(6) bond length is 2.56 Å. There are six inequivalent Se sites. In the first Se site, Se(1) is bonded in a rectangular see-saw-like geometry to one Nb(1), two equivalent Nb(4), and one Fe(1) atom. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to one Nb(1), two equivalent Nb(4), and one Fe(1) atom. In the third Se site, Se(3) is bonded in a rectangular see-saw-like geometry to one Nb(1), two equivalent Nb(4), and one Fe(1) atom. In the fourth Se site, Se(4) is bonded in a rectangular see-saw-like geometry to one Nb(2), two equivalent Nb(3), and one Fe(1) atom. In the fifth Se site, Se(5) is bonded in a rectangular see-saw-like geometry to one Nb(2), two equivalent Nb(3), and one Fe(1) atom. In the sixth Se site, Se(6) is bonded in a rectangular see-saw-like geometry to one Nb(2), two equivalent Nb(3), and one Fe(1) atom.