Mn(NbSe2)4 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to six equivalent Se(2) atoms to form distorted NbSe6 pentagonal pyramids that share edges with six equivalent Nb(2)Se6 pentagonal pyramids and faces with two equivalent Mn(1)Se6 octahedra. In the second Nb site, Nb(2) is bonded to two equivalent Se(1) and four equivalent Se(2) atoms to form distorted NbSe6 pentagonal pyramids that share corners with four equivalent Mn(1)Se6 octahedra, edges with two equivalent Nb(1)Se6 pentagonal pyramids, and edges with four equivalent Nb(2)Se6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 49°. Mn(1) is bonded to six equivalent Se(2) atoms to form MnSe6 octahedra that share corners with twelve equivalent Nb(2)Se6 pentagonal pyramids and faces with two equivalent Nb(1)Se6 pentagonal pyramids. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 3-coordinate geometry to three equivalent Nb(2) atoms. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to one Nb(1), two equivalent Nb(2), and one Mn(1) atom.
Mn(NbSe2)4 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to six equivalent Se(2) atoms to form distorted NbSe6 pentagonal pyramids that share edges with six equivalent Nb(2)Se6 pentagonal pyramids and faces with two equivalent Mn(1)Se6 octahedra. All Nb(1)-Se(2) bond lengths are 2.63 Å. In the second Nb site, Nb(2) is bonded to two equivalent Se(1) and four equivalent Se(2) atoms to form distorted NbSe6 pentagonal pyramids that share corners with four equivalent Mn(1)Se6 octahedra, edges with two equivalent Nb(1)Se6 pentagonal pyramids, and edges with four equivalent Nb(2)Se6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 49°. Both Nb(2)-Se(1) bond lengths are 2.58 Å. All Nb(2)-Se(2) bond lengths are 2.64 Å. Mn(1) is bonded to six equivalent Se(2) atoms to form MnSe6 octahedra that share corners with twelve equivalent Nb(2)Se6 pentagonal pyramids and faces with two equivalent Nb(1)Se6 pentagonal pyramids. All Mn(1)-Se(2) bond lengths are 2.63 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 3-coordinate geometry to three equivalent Nb(2) atoms. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to one Nb(1), two equivalent Nb(2), and one Mn(1) atom.