Nd2RhSi3 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Nd sites. In the first Nd site, Nd(1) is bonded to twelve equivalent Si(1) atoms to form NdSi12 cuboctahedra that share edges with twelve equivalent Nd(2)Si8Rh4 cuboctahedra, faces with two equivalent Nd(1)Si12 cuboctahedra, and faces with six equivalent Nd(2)Si8Rh4 cuboctahedra. In the second Nd site, Nd(2) is bonded to four equivalent Rh(1) and eight equivalent Si(1) atoms to form NdSi8Rh4 cuboctahedra that share edges with four equivalent Nd(1)Si12 cuboctahedra, edges with eight equivalent Nd(2)Si8Rh4 cuboctahedra, faces with two equivalent Nd(1)Si12 cuboctahedra, and faces with six equivalent Nd(2)Si8Rh4 cuboctahedra. Rh(1) is bonded in a 9-coordinate geometry to six equivalent Nd(2) and three equivalent Si(1) atoms. Si(1) is bonded in a 9-coordinate geometry to two equivalent Nd(1), four equivalent Nd(2), one Rh(1), and two equivalent Si(1) atoms.
Nd2RhSi3 crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Nd sites. In the first Nd site, Nd(1) is bonded to twelve equivalent Si(1) atoms to form NdSi12 cuboctahedra that share edges with twelve equivalent Nd(2)Si8Rh4 cuboctahedra, faces with two equivalent Nd(1)Si12 cuboctahedra, and faces with six equivalent Nd(2)Si8Rh4 cuboctahedra. There are six shorter (3.16 Å) and six longer (3.19 Å) Nd(1)-Si(1) bond lengths. In the second Nd site, Nd(2) is bonded to four equivalent Rh(1) and eight equivalent Si(1) atoms to form NdSi8Rh4 cuboctahedra that share edges with four equivalent Nd(1)Si12 cuboctahedra, edges with eight equivalent Nd(2)Si8Rh4 cuboctahedra, faces with two equivalent Nd(1)Si12 cuboctahedra, and faces with six equivalent Nd(2)Si8Rh4 cuboctahedra. There are two shorter (3.10 Å) and two longer (3.25 Å) Nd(2)-Rh(1) bond lengths. There are four shorter (3.13 Å) and four longer (3.21 Å) Nd(2)-Si(1) bond lengths. Rh(1) is bonded in a 9-coordinate geometry to six equivalent Nd(2) and three equivalent Si(1) atoms. All Rh(1)-Si(1) bond lengths are 2.40 Å. Si(1) is bonded in a 9-coordinate geometry to two equivalent Nd(1), four equivalent Nd(2), one Rh(1), and two equivalent Si(1) atoms. Both Si(1)-Si(1) bond lengths are 2.39 Å.