FeMoSi crystallizes in the orthorhombic Amm2 space group. There are seven inequivalent Mo sites. In the first Mo site, Mo(1) is bonded in a 16-coordinate geometry to one Mo(1), three equivalent Mo(2), three equivalent Fe(1), four equivalent Fe(2), one Si(3), two equivalent Si(1), and two equivalent Si(2) atoms. In the second Mo site, Mo(2) is bonded in a 16-coordinate geometry to one Mo(2); three Mo(1,1); two equivalent Fe(2); three equivalent Fe(1); one Si(1); two equivalent Si(3); and four equivalent Si(2) atoms. In the third Mo site, Mo(2) is bonded in a 16-coordinate geometry to one Mo(2); three Mo(1,1); two equivalent Fe(2); three equivalent Fe(1); one Si(1); two equivalent Si(3); and four equivalent Si(2) atoms. In the fourth Mo site, Mo(1) is bonded in a 16-coordinate geometry to one Mo(1); three Mo(2,2); three equivalent Fe(1); four equivalent Fe(2); one Si(3); two equivalent Si(1); and two equivalent Si(2) atoms. In the fifth Mo site, Mo(1) is bonded in a 16-coordinate geometry to one Mo(1), three equivalent Mo(2), three equivalent Fe(1), four equivalent Fe(2), one Si(3), two equivalent Si(1), and two equivalent Si(2) atoms. In the sixth Mo site, Mo(2) is bonded in a 16-coordinate geometry to one Mo(2); three Mo(1,1); two equivalent Fe(2); three equivalent Fe(1); one Si(1); two equivalent Si(3); and four equivalent Si(2) atoms. In the seventh Mo site, Mo(1) is bonded in a 16-coordinate geometry to one Mo(1); three Mo(2,2); three equivalent Fe(1); four equivalent Fe(2); one Si(3); two equivalent Si(1); and two equivalent Si(2) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three Mo(1,1); three equivalent Mo(2); two equivalent Fe(2); one Si(1); one Si(3); and two equivalent Si(2) atoms to form FeFe2Si4Mo6 cuboctahedra that share corners with two equivalent Si(3)Fe2Si4Mo6 cuboctahedra, corners with two equivalent Si(1)Fe6Mo6 cuboctahedra, corners with four equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, corners with four equivalent Si(2)Fe2Si4Mo6 cuboctahedra, edges with six equivalent Fe(1)Fe2Si4Mo6 cuboctahedra, faces with two equivalent Fe(1)Fe2Si4Mo6 cuboctahedra, faces with three equivalent Si(3)Fe2Si4Mo6 cuboctahedra, faces with three equivalent Si(1)Fe6Mo6 cuboctahedra, faces with six equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, and faces with six equivalent Si(2)Fe2Si4Mo6 cuboctahedra. In the second Fe site, Fe(2) is bonded to two Mo(2,2); four Mo(1,1,1,1); two equivalent Fe(1); two equivalent Fe(2); and two equivalent Si(1) atoms to form FeFe4Si2Mo6 cuboctahedra that share corners with four equivalent Fe(1)Fe2Si4Mo6 cuboctahedra, corners with four equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, corners with four equivalent Si(3)Fe2Si4Mo6 cuboctahedra, corners with six equivalent Si(2)Fe2Si4Mo6 cuboctahedra, edges with two equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, edges with four equivalent Si(2)Fe2Si4Mo6 cuboctahedra, faces with two equivalent Si(2)Fe2Si4Mo6 cuboctahedra, faces with two equivalent Si(3)Fe2Si4Mo6 cuboctahedra, faces with four equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, faces with four equivalent Si(1)Fe6Mo6 cuboctahedra, and faces with six equivalent Fe(1)Fe2Si4Mo6 cuboctahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to two Mo(2,2); four Mo(1,1); two equivalent Fe(1); and four equivalent Fe(2) atoms to form SiFe6Mo6 cuboctahedra that share corners with two equivalent Si(3)Fe2Si4Mo6 cuboctahedra, corners with four equivalent Fe(1)Fe2Si4Mo6 cuboctahedra, corners with four equivalent Si(1)Fe6Mo6 cuboctahedra, corners with eight equivalent Si(2)Fe2Si4Mo6 cuboctahedra, edges with two equivalent Si(1)Fe6Mo6 cuboctahedra, edges with four equivalent Si(3)Fe2Si4Mo6 cuboctahedra, faces with four equivalent Si(2)Fe2Si4Mo6 cuboctahedra, faces with six equivalent Fe(1)Fe2Si4Mo6 cuboctahedra, and faces with eight equivalent Fe(2)Fe4Si2Mo6 cuboctahedra. In the second Si site, Si(2) is bonded to two Mo(1,1); four Mo(2,2,2); two equivalent Fe(1); two equivalent Si(2); and two equivalent Si(3) atoms to form SiFe2Si4Mo6 cuboctahedra that share corners with four equivalent Fe(1)Fe2Si4Mo6 cuboctahedra, corners with four equivalent Si(2)Fe2Si4Mo6 cuboctahedra, corners with four equivalent Si(1)Fe6Mo6 cuboctahedra, corners with six equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, edges with two equivalent Si(2)Fe2Si4Mo6 cuboctahedra, edges with four equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, faces with two equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, faces with two equivalent Si(1)Fe6Mo6 cuboctahedra, faces with four equivalent Si(2)Fe2Si4Mo6 cuboctahedra, faces with four equivalent Si(3)Fe2Si4Mo6 cuboctahedra, and faces with six equivalent Fe(1)Fe2Si4Mo6 cuboctahedra. In the third Si site, Si(3) is bonded to two Mo(1,1); four Mo(2,2); two equivalent Fe(1); and four equivalent Si(2) atoms to form SiFe2Si4Mo6 cuboctahedra that share corners with two equivalent Si(1)Fe6Mo6 cuboctahedra, corners with four equivalent Fe(1)Fe2Si4Mo6 cuboctahedra, corners with four equivalent Si(3)Fe2Si4Mo6 cuboctahedra, corners with eight equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, edges with two equivalent Si(3)Fe2Si4Mo6 cuboctahedra, edges with four equivalent Si(1)Fe6Mo6 cuboctahedra, faces with four equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, faces with six equivalent Fe(1)Fe2Si4Mo6 cuboctahedra, and faces with eight equivalent Si(2)Fe2Si4Mo6 cuboctahedra.
FeMoSi crystallizes in the orthorhombic Amm2 space group. There are seven inequivalent Mo sites. In the first Mo site, Mo(1) is bonded in a 16-coordinate geometry to one Mo(1), three equivalent Mo(2), three equivalent Fe(1), four equivalent Fe(2), one Si(3), two equivalent Si(1), and two equivalent Si(2) atoms. The Mo(1)-Mo(1) bond length is 2.86 Å. All Mo(1)-Mo(2) bond lengths are 2.94 Å. All Mo(1)-Fe(1) bond lengths are 2.82 Å. There are two shorter (2.78 Å) and two longer (2.81 Å) Mo(1)-Fe(2) bond lengths. The Mo(1)-Si(3) bond length is 2.70 Å. Both Mo(1)-Si(1) bond lengths are 2.80 Å. Both Mo(1)-Si(2) bond lengths are 2.69 Å. In the second Mo site, Mo(2) is bonded in a 16-coordinate geometry to one Mo(2); three Mo(1,1); two equivalent Fe(2); three equivalent Fe(1); one Si(1); two equivalent Si(3); and four equivalent Si(2) atoms. The Mo(2)-Mo(2) bond length is 2.68 Å. Both Mo(2)-Mo(1) bond lengths are 2.94 Å. Both Mo(2)-Fe(2) bond lengths are 2.76 Å. There is one shorter (2.81 Å) and two longer (2.82 Å) Mo(2)-Fe(1) bond lengths. The Mo(2)-Si(1) bond length is 2.78 Å. Both Mo(2)-Si(3) bond lengths are 2.75 Å. All Mo(2)-Si(2) bond lengths are 2.75 Å. In the third Mo site, Mo(2) is bonded in a 16-coordinate geometry to one Mo(2); three Mo(1,1); two equivalent Fe(2); three equivalent Fe(1); one Si(1); two equivalent Si(3); and four equivalent Si(2) atoms. All Mo(2)-Mo(1,1) bond lengths are 2.94 Å. Both Mo(2)-Fe(2) bond lengths are 2.76 Å. There is one shorter (2.81 Å) and two longer (2.82 Å) Mo(2)-Fe(1) bond lengths. The Mo(2)-Si(1) bond length is 2.78 Å. Both Mo(2)-Si(3) bond lengths are 2.75 Å. All Mo(2)-Si(2) bond lengths are 2.75 Å. In the fourth Mo site, Mo(1) is bonded in a 16-coordinate geometry to one Mo(1); three Mo(2,2); three equivalent Fe(1); four equivalent Fe(2); one Si(3); two equivalent Si(1); and two equivalent Si(2) atoms. Both Mo(1)-Mo(2) bond lengths are 2.94 Å. All Mo(1)-Fe(1) bond lengths are 2.82 Å. There are two shorter (2.78 Å) and two longer (2.81 Å) Mo(1)-Fe(2) bond lengths. The Mo(1)-Si(3) bond length is 2.70 Å. Both Mo(1)-Si(1) bond lengths are 2.80 Å. Both Mo(1)-Si(2) bond lengths are 2.69 Å. In the fifth Mo site, Mo(1) is bonded in a 16-coordinate geometry to one Mo(1), three equivalent Mo(2), three equivalent Fe(1), four equivalent Fe(2), one Si(3), two equivalent Si(1), and two equivalent Si(2) atoms. The Mo(1)-Mo(1) bond length is 2.86 Å. All Mo(1)-Fe(1) bond lengths are 2.82 Å. There are two shorter (2.78 Å) and two longer (2.81 Å) Mo(1)-Fe(2) bond lengths. The Mo(1)-Si(3) bond length is 2.70 Å. Both Mo(1)-Si(1) bond lengths are 2.80 Å. Both Mo(1)-Si(2) bond lengths are 2.69 Å. In the sixth Mo site, Mo(2) is bonded in a 16-coordinate geometry to one Mo(2); three Mo(1,1); two equivalent Fe(2); three equivalent Fe(1); one Si(1); two equivalent Si(3); and four equivalent Si(2) atoms. The Mo(2)-Mo(2) bond length is 2.68 Å. The Mo(2)-Mo(1) bond length is 2.94 Å. Both Mo(2)-Fe(2) bond lengths are 2.76 Å. There is one shorter (2.81 Å) and two longer (2.82 Å) Mo(2)-Fe(1) bond lengths. The Mo(2)-Si(1) bond length is 2.78 Å. Both Mo(2)-Si(3) bond lengths are 2.75 Å. All Mo(2)-Si(2) bond lengths are 2.75 Å. In the seventh Mo site, Mo(1) is bonded in a 16-coordinate geometry to one Mo(1); three Mo(2,2); three equivalent Fe(1); four equivalent Fe(2); one Si(3); two equivalent Si(1); and two equivalent Si(2) atoms. All Mo(1)-Fe(1) bond lengths are 2.82 Å. There are two shorter (2.78 Å) and two longer (2.81 Å) Mo(1)-Fe(2) bond lengths. The Mo(1)-Si(3) bond length is 2.70 Å. Both Mo(1)-Si(1) bond lengths are 2.80 Å. Both Mo(1)-Si(2) bond lengths are 2.69 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three Mo(1,1); three equivalent Mo(2); two equivalent Fe(2); one Si(1); one Si(3); and two equivalent Si(2) atoms to form FeFe2Si4Mo6 cuboctahedra that share corners with two equivalent Si(3)Fe2Si4Mo6 cuboctahedra, corners with two equivalent Si(1)Fe6Mo6 cuboctahedra, corners with four equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, corners with four equivalent Si(2)Fe2Si4Mo6 cuboctahedra, edges with six equivalent Fe(1)Fe2Si4Mo6 cuboctahedra, faces with two equivalent Fe(1)Fe2Si4Mo6 cuboctahedra, faces with three equivalent Si(3)Fe2Si4Mo6 cuboctahedra, faces with three equivalent Si(1)Fe6Mo6 cuboctahedra, faces with six equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, and faces with six equivalent Si(2)Fe2Si4Mo6 cuboctahedra. Both Fe(1)-Fe(2) bond lengths are 2.40 Å. The Fe(1)-Si(1) bond length is 2.36 Å. The Fe(1)-Si(3) bond length is 2.30 Å. Both Fe(1)-Si(2) bond lengths are 2.30 Å. In the second Fe site, Fe(2) is bonded to two Mo(2,2); four Mo(1,1,1,1); two equivalent Fe(1); two equivalent Fe(2); and two equivalent Si(1) atoms to form FeFe4Si2Mo6 cuboctahedra that share corners with four equivalent Fe(1)Fe2Si4Mo6 cuboctahedra, corners with four equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, corners with four equivalent Si(3)Fe2Si4Mo6 cuboctahedra, corners with six equivalent Si(2)Fe2Si4Mo6 cuboctahedra, edges with two equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, edges with four equivalent Si(2)Fe2Si4Mo6 cuboctahedra, faces with two equivalent Si(2)Fe2Si4Mo6 cuboctahedra, faces with two equivalent Si(3)Fe2Si4Mo6 cuboctahedra, faces with four equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, faces with four equivalent Si(1)Fe6Mo6 cuboctahedra, and faces with six equivalent Fe(1)Fe2Si4Mo6 cuboctahedra. There is one shorter (2.34 Å) and one longer (2.47 Å) Fe(2)-Fe(2) bond length. There is one shorter (2.35 Å) and one longer (2.45 Å) Fe(2)-Si(1) bond length. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to two Mo(2,2); four Mo(1,1); two equivalent Fe(1); and four equivalent Fe(2) atoms to form SiFe6Mo6 cuboctahedra that share corners with two equivalent Si(3)Fe2Si4Mo6 cuboctahedra, corners with four equivalent Fe(1)Fe2Si4Mo6 cuboctahedra, corners with four equivalent Si(1)Fe6Mo6 cuboctahedra, corners with eight equivalent Si(2)Fe2Si4Mo6 cuboctahedra, edges with two equivalent Si(1)Fe6Mo6 cuboctahedra, edges with four equivalent Si(3)Fe2Si4Mo6 cuboctahedra, faces with four equivalent Si(2)Fe2Si4Mo6 cuboctahedra, faces with six equivalent Fe(1)Fe2Si4Mo6 cuboctahedra, and faces with eight equivalent Fe(2)Fe4Si2Mo6 cuboctahedra. In the second Si site, Si(2) is bonded to two Mo(1,1); four Mo(2,2,2); two equivalent Fe(1); two equivalent Si(2); and two equivalent Si(3) atoms to form SiFe2Si4Mo6 cuboctahedra that share corners with four equivalent Fe(1)Fe2Si4Mo6 cuboctahedra, corners with four equivalent Si(2)Fe2Si4Mo6 cuboctahedra, corners with four equivalent Si(1)Fe6Mo6 cuboctahedra, corners with six equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, edges with two equivalent Si(2)Fe2Si4Mo6 cuboctahedra, edges with four equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, faces with two equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, faces with two equivalent Si(1)Fe6Mo6 cuboctahedra, faces with four equivalent Si(2)Fe2Si4Mo6 cuboctahedra, faces with four equivalent Si(3)Fe2Si4Mo6 cuboctahedra, and faces with six equivalent Fe(1)Fe2Si4Mo6 cuboctahedra. There is one shorter (2.38 Å) and one longer (2.43 Å) Si(2)-Si(2) bond length. There is one shorter (2.38 Å) and one longer (2.42 Å) Si(2)-Si(3) bond length. In the third Si site, Si(3) is bonded to two Mo(1,1); four Mo(2,2); two equivalent Fe(1); and four equivalent Si(2) atoms to form SiFe2Si4Mo6 cuboctahedra that share corners with two equivalent Si(1)Fe6Mo6 cuboctahedra, corners with four equivalent Fe(1)Fe2Si4Mo6 cuboctahedra, corners with four equivalent Si(3)Fe2Si4Mo6 cuboctahedra, corners with eight equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, edges with two equivalent Si(3)Fe2Si4Mo6 cuboctahedra, edges with four equivalent Si(1)Fe6Mo6 cuboctahedra, faces with four equivalent Fe(2)Fe4Si2Mo6 cuboctahedra, faces with six equivalent Fe(1)Fe2Si4Mo6 cuboctahedra, and faces with eight equivalent Si(2)Fe2Si4Mo6 cuboctahedra.