In3Si is beta-derived structured and crystallizes in the hexagonal P6_3/mmc space group. In(1) is bonded to eight equivalent In(1) and four equivalent Si(1) atoms to form InIn8Si4 cuboctahedra that share corners with four equivalent Si(1)In12 cuboctahedra, corners with fourteen equivalent In(1)In8Si4 cuboctahedra, edges with six equivalent Si(1)In12 cuboctahedra, edges with twelve equivalent In(1)In8Si4 cuboctahedra, faces with four equivalent Si(1)In12 cuboctahedra, and faces with sixteen equivalent In(1)In8Si4 cuboctahedra. Si(1) is bonded to twelve equivalent In(1) atoms to form SiIn12 cuboctahedra that share corners with six equivalent Si(1)In12 cuboctahedra, corners with twelve equivalent In(1)In8Si4 cuboctahedra, edges with eighteen equivalent In(1)In8Si4 cuboctahedra, faces with eight equivalent Si(1)In12 cuboctahedra, and faces with twelve equivalent In(1)In8Si4 cuboctahedra.
In3Si is beta-derived structured and crystallizes in the hexagonal P6_3/mmc space group. In(1) is bonded to eight equivalent In(1) and four equivalent Si(1) atoms to form InIn8Si4 cuboctahedra that share corners with four equivalent Si(1)In12 cuboctahedra, corners with fourteen equivalent In(1)In8Si4 cuboctahedra, edges with six equivalent Si(1)In12 cuboctahedra, edges with twelve equivalent In(1)In8Si4 cuboctahedra, faces with four equivalent Si(1)In12 cuboctahedra, and faces with sixteen equivalent In(1)In8Si4 cuboctahedra. There are a spread of In(1)-In(1) bond distances ranging from 3.17-3.35 Å. There are two shorter (3.22 Å) and two longer (3.26 Å) In(1)-Si(1) bond lengths. Si(1) is bonded to twelve equivalent In(1) atoms to form SiIn12 cuboctahedra that share corners with six equivalent Si(1)In12 cuboctahedra, corners with twelve equivalent In(1)In8Si4 cuboctahedra, edges with eighteen equivalent In(1)In8Si4 cuboctahedra, faces with eight equivalent Si(1)In12 cuboctahedra, and faces with twelve equivalent In(1)In8Si4 cuboctahedra.