DOE OSTI2020
Mo6Fe3RhN2 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are six inequivalent Mo sites. In the first Mo site, Mo is bonded in a distorted bent 150 degrees geometry to five Fe, one Rh, and two equivalent N atoms. There are a spread of Mo–Fe bond distances ranging from 2.69–2.84 Å. The Mo–Rh bond length is 2.79 Å. Both Mo–N bond lengths are 2.10 Å. In the second Mo site, Mo is bonded in a distorted bent 150 degrees geometry to four Fe, two equivalent Rh, and two equivalent N atoms. There are a spread of Mo–Fe bond distances ranging from 2.69–2.90 Å. There are one shorter (2.77 Å) and one longer (2.82 Å) Mo–Rh bond lengths. Both Mo–N bond lengths are 2.10 Å. In the third Mo site, Mo is bonded in a distorted bent 150 degrees geometry to five Fe, one Rh, and two N atoms. There are a spread of Mo–Fe bond distances ranging from 2.66–2.83 Å. The Mo–Rh bond length is 2.80 Å. Both Mo–N bond lengths are 2.09 Å. In the fourth Mo site, Mo is bonded in a distorted bent 150 degrees geometry to four Fe, two equivalent Rh, and two N atoms. There are a spread of Mo–Fe bond distances ranging from 2.76–2.88 Å. There are one shorter (2.79 Å) and one longer (2.86 Å) Mo–Rh bond lengths. There are one shorter (2.09 Å) and one longer (2.10 Å) Mo–N bond lengths. In the fifth Mo site, Mo is bonded in a distorted bent 150 degrees geometry to four Fe, two equivalent Rh, and two N atoms. There are a spread of Mo–Fe bond distances ranging from 2.73–3.00 Å. There are one shorter (2.79 Å) and one longer (2.80 Å) Mo–Rh bond lengths. Both Mo–N bond lengths are 2.09 Å. In the sixth Mo site, Mo is bonded in a distorted bent 150 degrees geometry to five Fe, one Rh, and two N atoms. There are a spread of Mo–Fe bond distances ranging from 2.71–2.79 Å. The Mo–Rh bond length is 2.84 Å. There are one shorter (2.10 Å) and one longer (2.12 Å) Mo–N bond lengths. There are three inequivalent Fe sites. In the first Fe site, Fe is bonded to nine Mo and three Fe atoms to form FeFe3Mo9 cuboctahedra that share corners with four equivalent RhFe3Mo9 cuboctahedra, corners with eleven FeFe3Mo9 cuboctahedra, edges with three NMo6 octahedra, faces with four equivalent RhFe3Mo9 cuboctahedra, faces with six FeFe3Mo9 cuboctahedra, and faces with four NMo6 octahedra. There are a spread of Fe–Fe bond distances ranging from 2.40–2.44 Å. In the second Fe site, Fe is bonded to nine Mo, two equivalent Fe, and one Rh atom to form distorted FeFe2Mo9Rh cuboctahedra that share corners with five equivalent RhFe3Mo9 cuboctahedra, corners with ten FeFe3Mo9 cuboctahedra, edges with three NMo6 octahedra, faces with two equivalent RhFe3Mo9 cuboctahedra, faces with eight FeFe3Mo9 cuboctahedra, and faces with four NMo6 octahedra. The Fe–Rh bond length is 2.55 Å. In the third Fe site, Fe is bonded to nine Mo, one Fe, and two equivalent Rh atoms to form distorted FeFeMo9Rh2 cuboctahedra that share corners with four equivalent RhFe3Mo9 cuboctahedra, corners with eleven FeFe3Mo9 cuboctahedra, edges with three NMo6 octahedra, faces with two equivalent RhFe3Mo9 cuboctahedra, faces with eight FeFe3Mo9 cuboctahedra, and faces with four NMo6 octahedra. Both Fe–Rh bond lengths are 2.54 Å. Rh is bonded to nine Mo and three Fe atoms to form distorted RhFe3Mo9 cuboctahedra that share corners with two equivalent RhFe3Mo9 cuboctahedra, corners with thirteen FeFe3Mo9 cuboctahedra, edges with three NMo6 octahedra, faces with two equivalent RhFe3Mo9 cuboctahedra, faces with eight FeFe3Mo9 cuboctahedra, and faces with four NMo6 octahedra. There are two inequivalent N sites. In the first N site, N is bonded to six Mo atoms to form distorted NMo6 octahedra that share corners with six NMo6 octahedra, an edgeedge with one RhFe3Mo9 cuboctahedra, edges with five FeFe3Mo9 cuboctahedra, faces with two equivalent RhFe3Mo9 cuboctahedra, and faces with six FeFe3Mo9 cuboctahedra. The corner-sharing octahedra tilt angles range from 24–26°. In the second N site, N is bonded to six Mo atoms to form distorted NMo6 octahedra that share corners with six NMo6 octahedra, edges with two equivalent RhFe3Mo9 cuboctahedra, edges with four FeFe3Mo9 cuboctahedra, faces with two equivalent RhFe3Mo9 cuboctahedra, and faces with six FeFe3Mo9 cuboctahedra. The corner-sharing octahedra tilt angles range from 24–26°.