MgSi2 crystallizes in the triclinic P-1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 14-coordinate geometry to one Mg(1), one Mg(2), one Si(3), two equivalent Si(2), four equivalent Si(4), and five equivalent Si(1) atoms. In the second Mg site, Mg(2) is bonded in a 13-coordinate geometry to one Mg(1), two equivalent Mg(2), one Si(1), two equivalent Si(4), three equivalent Si(2), and four equivalent Si(3) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 10-coordinate geometry to one Mg(2), five equivalent Mg(1), one Si(1), one Si(2), and two equivalent Si(4) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Mg(1), three equivalent Mg(2), one Si(1), one Si(4), and two equivalent Si(3) atoms. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to one Mg(1), four equivalent Mg(2), one Si(3), one Si(4), and two equivalent Si(2) atoms. In the fourth Si site, Si(4) is bonded in a 10-coordinate geometry to two equivalent Mg(2), four equivalent Mg(1), one Si(2), one Si(3), and two equivalent Si(1) atoms.
MgSi2 crystallizes in the triclinic P-1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 14-coordinate geometry to one Mg(1), one Mg(2), one Si(3), two equivalent Si(2), four equivalent Si(4), and five equivalent Si(1) atoms. The Mg(1)-Mg(1) bond length is 2.90 Å. The Mg(1)-Mg(2) bond length is 3.06 Å. The Mg(1)-Si(3) bond length is 2.93 Å. There is one shorter (2.91 Å) and one longer (3.01 Å) Mg(1)-Si(2) bond length. There are a spread of Mg(1)-Si(4) bond distances ranging from 2.85-3.02 Å. There are a spread of Mg(1)-Si(1) bond distances ranging from 2.77-3.05 Å. In the second Mg site, Mg(2) is bonded in a 13-coordinate geometry to one Mg(1), two equivalent Mg(2), one Si(1), two equivalent Si(4), three equivalent Si(2), and four equivalent Si(3) atoms. There is one shorter (3.06 Å) and one longer (3.13 Å) Mg(2)-Mg(2) bond length. The Mg(2)-Si(1) bond length is 3.16 Å. There is one shorter (3.06 Å) and one longer (3.12 Å) Mg(2)-Si(4) bond length. There are a spread of Mg(2)-Si(2) bond distances ranging from 2.83-3.18 Å. There are a spread of Mg(2)-Si(3) bond distances ranging from 2.79-2.90 Å. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 10-coordinate geometry to one Mg(2), five equivalent Mg(1), one Si(1), one Si(2), and two equivalent Si(4) atoms. The Si(1)-Si(1) bond length is 2.54 Å. The Si(1)-Si(2) bond length is 2.46 Å. There is one shorter (2.62 Å) and one longer (2.64 Å) Si(1)-Si(4) bond length. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to two equivalent Mg(1), three equivalent Mg(2), one Si(1), one Si(4), and two equivalent Si(3) atoms. The Si(2)-Si(4) bond length is 2.52 Å. There is one shorter (2.55 Å) and one longer (2.57 Å) Si(2)-Si(3) bond length. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to one Mg(1), four equivalent Mg(2), one Si(3), one Si(4), and two equivalent Si(2) atoms. The Si(3)-Si(3) bond length is 2.67 Å. The Si(3)-Si(4) bond length is 2.47 Å. In the fourth Si site, Si(4) is bonded in a 10-coordinate geometry to two equivalent Mg(2), four equivalent Mg(1), one Si(2), one Si(3), and two equivalent Si(1) atoms.