Nd2Fe14Si3 crystallizes in the monoclinic C2/m space group. Nd(1) is bonded in a 19-coordinate geometry to two equivalent Fe(1), two equivalent Fe(5), three equivalent Fe(3), four equivalent Fe(2), six equivalent Fe(4), one Si(1), and one Si(2) atom. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent Nd(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(4), two equivalent Fe(5), and two equivalent Si(1) atoms to form distorted FeNd2Fe8Si2 cuboctahedra that share corners with two equivalent Fe(1)Nd2Fe8Si2 cuboctahedra, corners with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, corners with two equivalent Fe(3)Nd3Fe8Si cuboctahedra, corners with six equivalent Fe(4)Nd3Fe7Si2 cuboctahedra,  an edgeedge with one Fe(1)Nd2Fe8Si2 cuboctahedra, edges with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, edges with two equivalent Fe(4)Nd3Fe7Si2 cuboctahedra,  a faceface with one Fe(1)Nd2Fe8Si2 cuboctahedra, faces with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, faces with four equivalent Fe(3)Nd3Fe8Si cuboctahedra, and faces with six equivalent Fe(4)Nd3Fe7Si2 cuboctahedra. In the second Fe site, Fe(2) is bonded in a 12-coordinate geometry to two equivalent Nd(1), one Fe(1), one Fe(2), one Fe(3), one Fe(5), three equivalent Fe(4), one Si(2), and two equivalent Si(1) atoms. In the third Fe site, Fe(3) is bonded to three equivalent Nd(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(4), two equivalent Fe(5), and one Si(1) atom to form FeNd3Fe8Si cuboctahedra that share corners with two equivalent Fe(1)Nd2Fe8Si2 cuboctahedra, corners with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, corners with four equivalent Fe(3)Nd3Fe8Si cuboctahedra, corners with six equivalent Fe(4)Nd3Fe7Si2 cuboctahedra,  an edgeedge with one Fe(3)Nd3Fe8Si cuboctahedra, edges with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, edges with four equivalent Fe(4)Nd3Fe7Si2 cuboctahedra,  a faceface with one Fe(3)Nd3Fe8Si cuboctahedra, faces with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, faces with four equivalent Fe(1)Nd2Fe8Si2 cuboctahedra, and faces with six equivalent Fe(4)Nd3Fe7Si2 cuboctahedra. In the fourth Fe site, Fe(4) is bonded to three equivalent Nd(1), one Fe(1), one Fe(3), one Fe(4), one Fe(5), three equivalent Fe(2), one Si(1), and one Si(2) atom to form distorted FeNd3Fe7Si2 cuboctahedra that share corners with three equivalent Fe(1)Nd2Fe8Si2 cuboctahedra, corners with three equivalent Fe(3)Nd3Fe8Si cuboctahedra, corners with four equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, corners with seven equivalent Fe(4)Nd3Fe7Si2 cuboctahedra,  an edgeedge with one Fe(1)Nd2Fe8Si2 cuboctahedra, edges with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, edges with two equivalent Fe(3)Nd3Fe8Si cuboctahedra, edges with three equivalent Fe(4)Nd3Fe7Si2 cuboctahedra, faces with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, faces with three equivalent Fe(1)Nd2Fe8Si2 cuboctahedra, faces with three equivalent Fe(3)Nd3Fe8Si cuboctahedra, and faces with four equivalent Fe(4)Nd3Fe7Si2 cuboctahedra. In the fifth Fe site, Fe(5) is bonded to two equivalent Nd(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(4), and two equivalent Si(1) atoms to form distorted FeNd2Fe8Si2 cuboctahedra that share corners with two equivalent Fe(1)Nd2Fe8Si2 cuboctahedra, corners with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, corners with two equivalent Fe(3)Nd3Fe8Si cuboctahedra, corners with eight equivalent Fe(4)Nd3Fe7Si2 cuboctahedra, edges with two equivalent Fe(1)Nd2Fe8Si2 cuboctahedra, edges with two equivalent Fe(3)Nd3Fe8Si cuboctahedra, edges with four equivalent Fe(4)Nd3Fe7Si2 cuboctahedra, faces with two equivalent Fe(1)Nd2Fe8Si2 cuboctahedra, faces with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, faces with two equivalent Fe(3)Nd3Fe8Si cuboctahedra, and faces with four equivalent Fe(4)Nd3Fe7Si2 cuboctahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 14-coordinate geometry to one Nd(1), one Fe(3), two equivalent Fe(1), two equivalent Fe(4), two equivalent Fe(5), four equivalent Fe(2), one Si(1), and one Si(2) atom. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to two equivalent Nd(1), four equivalent Fe(2), four equivalent Fe(4), and two equivalent Si(1) atoms.
Nd2Fe14Si3 crystallizes in the monoclinic C2/m space group. Nd(1) is bonded in a 19-coordinate geometry to two equivalent Fe(1), two equivalent Fe(5), three equivalent Fe(3), four equivalent Fe(2), six equivalent Fe(4), one Si(1), and one Si(2) atom. Both Nd(1)-Fe(1) bond lengths are 3.07 Å. Both Nd(1)-Fe(5) bond lengths are 3.29 Å. There are a spread of Nd(1)-Fe(3) bond distances ranging from 3.04-3.26 Å. There are two shorter (2.98 Å) and two longer (3.05 Å) Nd(1)-Fe(2) bond lengths. There are two shorter (3.12 Å) and four longer (3.20 Å) Nd(1)-Fe(4) bond lengths. The Nd(1)-Si(1) bond length is 3.09 Å. The Nd(1)-Si(2) bond length is 3.37 Å. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent Nd(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(4), two equivalent Fe(5), and two equivalent Si(1) atoms to form distorted FeNd2Fe8Si2 cuboctahedra that share corners with two equivalent Fe(1)Nd2Fe8Si2 cuboctahedra, corners with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, corners with two equivalent Fe(3)Nd3Fe8Si cuboctahedra, corners with six equivalent Fe(4)Nd3Fe7Si2 cuboctahedra,  an edgeedge with one Fe(1)Nd2Fe8Si2 cuboctahedra, edges with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, edges with two equivalent Fe(4)Nd3Fe7Si2 cuboctahedra,  a faceface with one Fe(1)Nd2Fe8Si2 cuboctahedra, faces with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, faces with four equivalent Fe(3)Nd3Fe8Si cuboctahedra, and faces with six equivalent Fe(4)Nd3Fe7Si2 cuboctahedra. Both Fe(1)-Fe(2) bond lengths are 2.46 Å. Both Fe(1)-Fe(3) bond lengths are 2.71 Å. Both Fe(1)-Fe(4) bond lengths are 2.49 Å. Both Fe(1)-Fe(5) bond lengths are 2.44 Å. Both Fe(1)-Si(1) bond lengths are 2.64 Å. In the second Fe site, Fe(2) is bonded in a 12-coordinate geometry to two equivalent Nd(1), one Fe(1), one Fe(2), one Fe(3), one Fe(5), three equivalent Fe(4), one Si(2), and two equivalent Si(1) atoms. The Fe(2)-Fe(2) bond length is 2.42 Å. The Fe(2)-Fe(3) bond length is 2.53 Å. The Fe(2)-Fe(5) bond length is 2.46 Å. There are a spread of Fe(2)-Fe(4) bond distances ranging from 2.51-2.68 Å. The Fe(2)-Si(2) bond length is 2.42 Å. There is one shorter (2.65 Å) and one longer (2.94 Å) Fe(2)-Si(1) bond length. In the third Fe site, Fe(3) is bonded to three equivalent Nd(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(4), two equivalent Fe(5), and one Si(1) atom to form FeNd3Fe8Si cuboctahedra that share corners with two equivalent Fe(1)Nd2Fe8Si2 cuboctahedra, corners with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, corners with four equivalent Fe(3)Nd3Fe8Si cuboctahedra, corners with six equivalent Fe(4)Nd3Fe7Si2 cuboctahedra,  an edgeedge with one Fe(3)Nd3Fe8Si cuboctahedra, edges with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, edges with four equivalent Fe(4)Nd3Fe7Si2 cuboctahedra,  a faceface with one Fe(3)Nd3Fe8Si cuboctahedra, faces with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, faces with four equivalent Fe(1)Nd2Fe8Si2 cuboctahedra, and faces with six equivalent Fe(4)Nd3Fe7Si2 cuboctahedra. Both Fe(3)-Fe(4) bond lengths are 2.46 Å. Both Fe(3)-Fe(5) bond lengths are 2.44 Å. The Fe(3)-Si(1) bond length is 2.51 Å. In the fourth Fe site, Fe(4) is bonded to three equivalent Nd(1), one Fe(1), one Fe(3), one Fe(4), one Fe(5), three equivalent Fe(2), one Si(1), and one Si(2) atom to form distorted FeNd3Fe7Si2 cuboctahedra that share corners with three equivalent Fe(1)Nd2Fe8Si2 cuboctahedra, corners with three equivalent Fe(3)Nd3Fe8Si cuboctahedra, corners with four equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, corners with seven equivalent Fe(4)Nd3Fe7Si2 cuboctahedra,  an edgeedge with one Fe(1)Nd2Fe8Si2 cuboctahedra, edges with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, edges with two equivalent Fe(3)Nd3Fe8Si cuboctahedra, edges with three equivalent Fe(4)Nd3Fe7Si2 cuboctahedra, faces with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, faces with three equivalent Fe(1)Nd2Fe8Si2 cuboctahedra, faces with three equivalent Fe(3)Nd3Fe8Si cuboctahedra, and faces with four equivalent Fe(4)Nd3Fe7Si2 cuboctahedra. The Fe(4)-Fe(4) bond length is 2.56 Å. The Fe(4)-Fe(5) bond length is 2.44 Å. The Fe(4)-Si(1) bond length is 2.61 Å. The Fe(4)-Si(2) bond length is 2.39 Å. In the fifth Fe site, Fe(5) is bonded to two equivalent Nd(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Fe(3), two equivalent Fe(4), and two equivalent Si(1) atoms to form distorted FeNd2Fe8Si2 cuboctahedra that share corners with two equivalent Fe(1)Nd2Fe8Si2 cuboctahedra, corners with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, corners with two equivalent Fe(3)Nd3Fe8Si cuboctahedra, corners with eight equivalent Fe(4)Nd3Fe7Si2 cuboctahedra, edges with two equivalent Fe(1)Nd2Fe8Si2 cuboctahedra, edges with two equivalent Fe(3)Nd3Fe8Si cuboctahedra, edges with four equivalent Fe(4)Nd3Fe7Si2 cuboctahedra, faces with two equivalent Fe(1)Nd2Fe8Si2 cuboctahedra, faces with two equivalent Fe(5)Nd2Fe8Si2 cuboctahedra, faces with two equivalent Fe(3)Nd3Fe8Si cuboctahedra, and faces with four equivalent Fe(4)Nd3Fe7Si2 cuboctahedra. Both Fe(5)-Si(1) bond lengths are 2.49 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 14-coordinate geometry to one Nd(1), one Fe(3), two equivalent Fe(1), two equivalent Fe(4), two equivalent Fe(5), four equivalent Fe(2), one Si(1), and one Si(2) atom. The Si(1)-Si(1) bond length is 2.50 Å. The Si(1)-Si(2) bond length is 2.79 Å. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to two equivalent Nd(1), four equivalent Fe(2), four equivalent Fe(4), and two equivalent Si(1) atoms.