Sr4Zn3Si5 is hexagonal omega structure-derived structured and crystallizes in the hexagonal P-6m2 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to three equivalent Zn(2), three equivalent Si(1), three equivalent Si(2), and three equivalent Si(4) atoms to form SrZn3Si9 cuboctahedra that share edges with six equivalent Sr(1)Zn3Si9 cuboctahedra, edges with six equivalent Sr(2)Zn6Si6 cuboctahedra,  a faceface with one Sr(2)Zn6Si6 cuboctahedra, and faces with seven equivalent Sr(1)Zn3Si9 cuboctahedra. In the second Sr site, Sr(2) is bonded to three equivalent Zn(1), three equivalent Zn(2), three equivalent Si(1), and three equivalent Si(3) atoms to form SrZn6Si6 cuboctahedra that share edges with six equivalent Sr(1)Zn3Si9 cuboctahedra, edges with six equivalent Sr(2)Zn6Si6 cuboctahedra,  a faceface with one Sr(1)Zn3Si9 cuboctahedra, and faces with seven equivalent Sr(2)Zn6Si6 cuboctahedra. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded in a distorted trigonal planar geometry to six equivalent Sr(2) and three equivalent Si(3) atoms. In the second Zn site, Zn(2) is bonded in a distorted trigonal planar geometry to three equivalent Sr(1), three equivalent Sr(2), and three equivalent Si(1) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted trigonal planar geometry to three equivalent Sr(1), three equivalent Sr(2), and three equivalent Zn(2) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to six equivalent Sr(1) and three equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a distorted trigonal planar geometry to six equivalent Sr(2) and three equivalent Zn(1) atoms. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to six equivalent Sr(1) and three equivalent Si(2) atoms.
Sr4Zn3Si5 is hexagonal omega structure-derived structured and crystallizes in the hexagonal P-6m2 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to three equivalent Zn(2), three equivalent Si(1), three equivalent Si(2), and three equivalent Si(4) atoms to form SrZn3Si9 cuboctahedra that share edges with six equivalent Sr(1)Zn3Si9 cuboctahedra, edges with six equivalent Sr(2)Zn6Si6 cuboctahedra,  a faceface with one Sr(2)Zn6Si6 cuboctahedra, and faces with seven equivalent Sr(1)Zn3Si9 cuboctahedra. All Sr(1)-Zn(2) bond lengths are 3.33 Å. All Sr(1)-Si(1) bond lengths are 3.36 Å. All Sr(1)-Si(2) bond lengths are 3.38 Å. All Sr(1)-Si(4) bond lengths are 3.38 Å. In the second Sr site, Sr(2) is bonded to three equivalent Zn(1), three equivalent Zn(2), three equivalent Si(1), and three equivalent Si(3) atoms to form SrZn6Si6 cuboctahedra that share edges with six equivalent Sr(1)Zn3Si9 cuboctahedra, edges with six equivalent Sr(2)Zn6Si6 cuboctahedra,  a faceface with one Sr(1)Zn3Si9 cuboctahedra, and faces with seven equivalent Sr(2)Zn6Si6 cuboctahedra. All Sr(2)-Zn(1) bond lengths are 3.36 Å. All Sr(2)-Zn(2) bond lengths are 3.37 Å. All Sr(2)-Si(1) bond lengths are 3.35 Å. All Sr(2)-Si(3) bond lengths are 3.36 Å. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded in a distorted trigonal planar geometry to six equivalent Sr(2) and three equivalent Si(3) atoms. All Zn(1)-Si(3) bond lengths are 2.46 Å. In the second Zn site, Zn(2) is bonded in a distorted trigonal planar geometry to three equivalent Sr(1), three equivalent Sr(2), and three equivalent Si(1) atoms. All Zn(2)-Si(1) bond lengths are 2.46 Å. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted trigonal planar geometry to three equivalent Sr(1), three equivalent Sr(2), and three equivalent Zn(2) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to six equivalent Sr(1) and three equivalent Si(4) atoms. All Si(2)-Si(4) bond lengths are 2.46 Å. In the third Si site, Si(3) is bonded in a distorted trigonal planar geometry to six equivalent Sr(2) and three equivalent Zn(1) atoms. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to six equivalent Sr(1) and three equivalent Si(2) atoms.