Si3CaC4 is lead oxide-derived structured and crystallizes in the trigonal R3m space group. Ca(1) is bonded in a distorted rectangular see-saw-like geometry to one C(4) and three equivalent C(3) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one C(1) and three equivalent C(4) atoms to form corner-sharing SiC4 tetrahedra. In the second Si site, Si(2) is bonded to one C(2) and three equivalent C(1) atoms to form corner-sharing SiC4 tetrahedra. In the third Si site, Si(3) is bonded to one C(3) and three equivalent C(2) atoms to form corner-sharing SiC4 tetrahedra. There are four inequivalent C sites. In the first C site, C(1) is bonded to one Si(1) and three equivalent Si(2) atoms to form CSi4 tetrahedra that share corners with three equivalent C(4)CaSi3 tetrahedra, corners with three equivalent C(2)Si4 tetrahedra, and corners with six equivalent C(1)Si4 tetrahedra. In the second C site, C(2) is bonded to one Si(2) and three equivalent Si(3) atoms to form corner-sharing CSi4 tetrahedra. In the third C site, C(3) is bonded in a distorted rectangular see-saw-like geometry to three equivalent Ca(1) and one Si(3) atom. In the fourth C site, C(4) is bonded to one Ca(1) and three equivalent Si(1) atoms to form CCaSi3 tetrahedra that share corners with three equivalent C(1)Si4 tetrahedra and corners with six equivalent C(4)CaSi3 tetrahedra.
Si3CaC4 is lead oxide-derived structured and crystallizes in the trigonal R3m space group. Ca(1) is bonded in a distorted rectangular see-saw-like geometry to one C(4) and three equivalent C(3) atoms. The Ca(1)-C(4) bond length is 2.47 Å. All Ca(1)-C(3) bond lengths are 2.39 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one C(1) and three equivalent C(4) atoms to form corner-sharing SiC4 tetrahedra. The Si(1)-C(1) bond length is 1.96 Å. All Si(1)-C(4) bond lengths are 1.89 Å. In the second Si site, Si(2) is bonded to one C(2) and three equivalent C(1) atoms to form corner-sharing SiC4 tetrahedra. The Si(2)-C(2) bond length is 1.92 Å. All Si(2)-C(1) bond lengths are 1.91 Å. In the third Si site, Si(3) is bonded to one C(3) and three equivalent C(2) atoms to form corner-sharing SiC4 tetrahedra. The Si(3)-C(3) bond length is 1.85 Å. All Si(3)-C(2) bond lengths are 1.93 Å. There are four inequivalent C sites. In the first C site, C(1) is bonded to one Si(1) and three equivalent Si(2) atoms to form CSi4 tetrahedra that share corners with three equivalent C(4)CaSi3 tetrahedra, corners with three equivalent C(2)Si4 tetrahedra, and corners with six equivalent C(1)Si4 tetrahedra. In the second C site, C(2) is bonded to one Si(2) and three equivalent Si(3) atoms to form corner-sharing CSi4 tetrahedra. In the third C site, C(3) is bonded in a distorted rectangular see-saw-like geometry to three equivalent Ca(1) and one Si(3) atom. In the fourth C site, C(4) is bonded to one Ca(1) and three equivalent Si(1) atoms to form CCaSi3 tetrahedra that share corners with three equivalent C(1)Si4 tetrahedra and corners with six equivalent C(4)CaSi3 tetrahedra.