Mo12NiSi3 crystallizes in the orthorhombic Pmmm space group. There are five inequivalent Mo sites. In the first Mo site, Mo(1) is bonded in a 6-coordinate geometry to one Mo(1), one Mo(2), two equivalent Ni(1), and two equivalent Si(2) atoms. In the second Mo site, Mo(2) is bonded in a 6-coordinate geometry to one Mo(1), one Mo(2), two equivalent Si(1), and two equivalent Si(2) atoms. In the third Mo site, Mo(3) is bonded in a 6-coordinate geometry to two equivalent Mo(3), one Ni(1), one Si(1), and two equivalent Si(2) atoms. In the fourth Mo site, Mo(4) is bonded in a 6-coordinate geometry to two equivalent Mo(4), two equivalent Ni(1), and two equivalent Si(2) atoms. In the fifth Mo site, Mo(5) is bonded in a 6-coordinate geometry to two equivalent Mo(5), two equivalent Si(1), and two equivalent Si(2) atoms. Ni(1) is bonded to four equivalent Mo(1), four equivalent Mo(3), and four equivalent Mo(4) atoms to form NiMo12 cuboctahedra that share edges with two equivalent Si(1)Mo12 cuboctahedra, edges with four equivalent Ni(1)Mo12 cuboctahedra, and faces with eight equivalent Si(2)Mo12 cuboctahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to four equivalent Mo(2), four equivalent Mo(3), and four equivalent Mo(5) atoms to form SiMo12 cuboctahedra that share edges with two equivalent Ni(1)Mo12 cuboctahedra, edges with four equivalent Si(1)Mo12 cuboctahedra, and faces with eight equivalent Si(2)Mo12 cuboctahedra. In the second Si site, Si(2) is bonded to two equivalent Mo(1), two equivalent Mo(2), two equivalent Mo(4), two equivalent Mo(5), and four equivalent Mo(3) atoms to form SiMo12 cuboctahedra that share edges with six equivalent Si(2)Mo12 cuboctahedra, faces with four equivalent Ni(1)Mo12 cuboctahedra, and faces with four equivalent Si(1)Mo12 cuboctahedra.
Mo12NiSi3 crystallizes in the orthorhombic Pmmm space group. There are five inequivalent Mo sites. In the first Mo site, Mo(1) is bonded in a 6-coordinate geometry to one Mo(1), one Mo(2), two equivalent Ni(1), and two equivalent Si(2) atoms. The Mo(1)-Mo(1) bond length is 2.47 Å. The Mo(1)-Mo(2) bond length is 2.47 Å. Both Mo(1)-Ni(1) bond lengths are 2.75 Å. Both Mo(1)-Si(2) bond lengths are 2.75 Å. In the second Mo site, Mo(2) is bonded in a 6-coordinate geometry to one Mo(1), one Mo(2), two equivalent Si(1), and two equivalent Si(2) atoms. The Mo(2)-Mo(2) bond length is 2.45 Å. Both Mo(2)-Si(1) bond lengths are 2.75 Å. Both Mo(2)-Si(2) bond lengths are 2.76 Å. In the third Mo site, Mo(3) is bonded in a 6-coordinate geometry to two equivalent Mo(3), one Ni(1), one Si(1), and two equivalent Si(2) atoms. Both Mo(3)-Mo(3) bond lengths are 2.46 Å. The Mo(3)-Ni(1) bond length is 2.75 Å. The Mo(3)-Si(1) bond length is 2.76 Å. Both Mo(3)-Si(2) bond lengths are 2.75 Å. In the fourth Mo site, Mo(4) is bonded in a 6-coordinate geometry to two equivalent Mo(4), two equivalent Ni(1), and two equivalent Si(2) atoms. Both Mo(4)-Mo(4) bond lengths are 2.46 Å. Both Mo(4)-Ni(1) bond lengths are 2.75 Å. Both Mo(4)-Si(2) bond lengths are 2.75 Å. In the fifth Mo site, Mo(5) is bonded in a 6-coordinate geometry to two equivalent Mo(5), two equivalent Si(1), and two equivalent Si(2) atoms. There is one shorter (2.45 Å) and one longer (2.47 Å) Mo(5)-Mo(5) bond length. Both Mo(5)-Si(1) bond lengths are 2.75 Å. Both Mo(5)-Si(2) bond lengths are 2.76 Å. Ni(1) is bonded to four equivalent Mo(1), four equivalent Mo(3), and four equivalent Mo(4) atoms to form NiMo12 cuboctahedra that share edges with two equivalent Si(1)Mo12 cuboctahedra, edges with four equivalent Ni(1)Mo12 cuboctahedra, and faces with eight equivalent Si(2)Mo12 cuboctahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to four equivalent Mo(2), four equivalent Mo(3), and four equivalent Mo(5) atoms to form SiMo12 cuboctahedra that share edges with two equivalent Ni(1)Mo12 cuboctahedra, edges with four equivalent Si(1)Mo12 cuboctahedra, and faces with eight equivalent Si(2)Mo12 cuboctahedra. In the second Si site, Si(2) is bonded to two equivalent Mo(1), two equivalent Mo(2), two equivalent Mo(4), two equivalent Mo(5), and four equivalent Mo(3) atoms to form SiMo12 cuboctahedra that share edges with six equivalent Si(2)Mo12 cuboctahedra, faces with four equivalent Ni(1)Mo12 cuboctahedra, and faces with four equivalent Si(1)Mo12 cuboctahedra.