SmCoSi2 crystallizes in the orthorhombic Cmcm space group. Sm(1) is bonded in a 14-coordinate geometry to four equivalent Co(1), four equivalent Si(1), and six equivalent Si(2) atoms. Co(1) is bonded in a 9-coordinate geometry to four equivalent Sm(1), one Si(2), and four equivalent Si(1) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to four equivalent Sm(1) and four equivalent Co(1) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to six equivalent Sm(1), one Co(1), and two equivalent Si(2) atoms.
SmCoSi2 crystallizes in the orthorhombic Cmcm space group. Sm(1) is bonded in a 14-coordinate geometry to four equivalent Co(1), four equivalent Si(1), and six equivalent Si(2) atoms. All Sm(1)-Co(1) bond lengths are 3.10 Å. There are two shorter (3.06 Å) and two longer (3.09 Å) Sm(1)-Si(1) bond lengths. There are four shorter (3.05 Å) and two longer (3.21 Å) Sm(1)-Si(2) bond lengths. Co(1) is bonded in a 9-coordinate geometry to four equivalent Sm(1), one Si(2), and four equivalent Si(1) atoms. The Co(1)-Si(2) bond length is 2.23 Å. There are two shorter (2.30 Å) and two longer (2.34 Å) Co(1)-Si(1) bond lengths. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to four equivalent Sm(1) and four equivalent Co(1) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to six equivalent Sm(1), one Co(1), and two equivalent Si(2) atoms. Both Si(2)-Si(2) bond lengths are 2.46 Å.