MgSi2 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded in a 9-coordinate geometry to four equivalent Si(2) and five 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 five equivalent Mg(1) and three equivalent Si(2) atoms. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to four equivalent Mg(1), one Si(2), and three equivalent Si(1) atoms.
MgSi2 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded in a 9-coordinate geometry to four equivalent Si(2) and five equivalent Si(1) atoms. There are two shorter (3.01 Å) and two longer (3.06 Å) Mg(1)-Si(2) bond lengths. There are a spread of Mg(1)-Si(1) bond distances ranging from 2.80-3.05 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to five equivalent Mg(1) and three equivalent Si(2) atoms. There are two shorter (2.44 Å) and one longer (2.54 Å) Si(1)-Si(2) bond length. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to four equivalent Mg(1), one Si(2), and three equivalent Si(1) atoms. The Si(2)-Si(2) bond length is 2.39 Å.