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 8-coordinate geometry to one Si(1), two equivalent Si(3), two equivalent Si(4), and three equivalent Si(2) atoms. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one Si(2), two equivalent Si(4), and three equivalent Si(1) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to one Mg(1), three equivalent Mg(2), one Si(1), and two equivalent Si(4) atoms. In the second Si site, Si(2) is bonded to one Mg(2), three equivalent Mg(1), and three equivalent Si(3) atoms to form distorted edge-sharing SiMg4Si3 pentagonal bipyramids. In the third Si site, Si(3) is bonded in a 6-coordinate geometry to two equivalent Mg(1), one Si(4), and three equivalent Si(2) atoms. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to two equivalent Mg(1), two equivalent Mg(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 8-coordinate geometry to one Si(1), two equivalent Si(3), two equivalent Si(4), and three equivalent Si(2) atoms. The Mg(1)-Si(1) bond length is 2.88 Å. There is one shorter (2.85 Å) and one longer (2.90 Å) Mg(1)-Si(3) bond length. There is one shorter (2.93 Å) and one longer (3.07 Å) Mg(1)-Si(4) bond length. There are a spread of Mg(1)-Si(2) bond distances ranging from 2.79-2.97 Å. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one Si(2), two equivalent Si(4), and three equivalent Si(1) atoms. The Mg(2)-Si(2) bond length is 3.08 Å. There is one shorter (2.88 Å) and one longer (2.91 Å) Mg(2)-Si(4) bond length. There are a spread of Mg(2)-Si(1) bond distances ranging from 2.91-3.03 Å. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to one Mg(1), three equivalent Mg(2), one Si(1), and two equivalent Si(4) atoms. The Si(1)-Si(1) bond length is 2.41 Å. There is one shorter (2.39 Å) and one longer (2.42 Å) Si(1)-Si(4) bond length. In the second Si site, Si(2) is bonded to one Mg(2), three equivalent Mg(1), and three equivalent Si(3) atoms to form distorted edge-sharing SiMg4Si3 pentagonal bipyramids. There are a spread of Si(2)-Si(3) bond distances ranging from 2.38-2.50 Å. In the third Si site, Si(3) is bonded in a 6-coordinate geometry to two equivalent Mg(1), one Si(4), and three equivalent Si(2) atoms. The Si(3)-Si(4) bond length is 2.37 Å. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), one Si(3), and two equivalent Si(1) atoms.