Nb3RhSe6 is Ilmenite-like structured and crystallizes in the hexagonal P6_322 space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to six equivalent Se(1) atoms to form distorted NbSe6 pentagonal pyramids that share corners with six equivalent Rh(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 47°. In the second Nb site, Nb(2) is bonded in a 6-coordinate geometry to six equivalent Se(1) atoms. Rh(1) is bonded to six equivalent Se(1) atoms to form RhSe6 octahedra that share corners with six equivalent Nb(1)Se6 pentagonal pyramids. Se(1) is bonded in a distorted rectangular see-saw-like geometry to one Nb(1), two equivalent Nb(2), and one Rh(1) atom.
Nb3RhSe6 is Ilmenite-like structured and crystallizes in the hexagonal P6_322 space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to six equivalent Se(1) atoms to form distorted NbSe6 pentagonal pyramids that share corners with six equivalent Rh(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 47°. All Nb(1)-Se(1) bond lengths are 2.61 Å. In the second Nb site, Nb(2) is bonded in a 6-coordinate geometry to six equivalent Se(1) atoms. There are three shorter (2.60 Å) and three longer (2.65 Å) Nb(2)-Se(1) bond lengths. Rh(1) is bonded to six equivalent Se(1) atoms to form RhSe6 octahedra that share corners with six equivalent Nb(1)Se6 pentagonal pyramids. All Rh(1)-Se(1) bond lengths are 2.53 Å. Se(1) is bonded in a distorted rectangular see-saw-like geometry to one Nb(1), two equivalent Nb(2), and one Rh(1) atom.