CaIr3Si7 crystallizes in the trigonal R-3c space group. Ca(1) is bonded in a 18-coordinate geometry to six equivalent Ir(1) and twelve equivalent Si(1) atoms. Ir(1) is bonded in a 9-coordinate geometry to two equivalent Ca(1), one Si(2), and six equivalent Si(1) atoms. There are two inequivalent Si sites. In the first Si site, Si(2) is bonded in a trigonal planar geometry to three equivalent Ir(1) atoms. In the second Si site, Si(1) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and three equivalent Ir(1) atoms.
CaIr3Si7 crystallizes in the trigonal R-3c space group. Ca(1) is bonded in a 18-coordinate geometry to six equivalent Ir(1) and twelve equivalent Si(1) atoms. All Ca(1)-Ir(1) bond lengths are 3.09 Å. There are six shorter (3.14 Å) and six longer (3.19 Å) Ca(1)-Si(1) bond lengths. Ir(1) is bonded in a 9-coordinate geometry to two equivalent Ca(1), one Si(2), and six equivalent Si(1) atoms. The Ir(1)-Si(2) bond length is 2.45 Å. There are a spread of Ir(1)-Si(1) bond distances ranging from 2.46-2.54 Å. There are two inequivalent Si sites. In the first Si site, Si(2) is bonded in a trigonal planar geometry to three equivalent Ir(1) atoms. In the second Si site, Si(1) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and three equivalent Ir(1) atoms.