Mg3Si2 crystallizes in the triclinic P-1 space group. There are six inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 5-coordinate geometry to two equivalent Si(1) and three equivalent Si(2) atoms. In the second Mg site, Mg(2) is bonded in a 5-coordinate geometry to one Si(3), two equivalent Si(1), and three equivalent Si(2) atoms. In the third Mg site, Mg(3) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), one Si(4), and two equivalent Si(3) atoms. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to two equivalent Si(3) and three equivalent Si(4) atoms. In the fifth Mg site, Mg(5) is bonded in a 3-coordinate geometry to one Si(1), one Si(4), and two equivalent Si(3) atoms. In the sixth Mg site, Mg(6) is bonded in a 4-coordinate geometry to one Si(1), one Si(2), one Si(3), and one Si(4) atom. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(5), one Mg(6), two equivalent Mg(1), two equivalent Mg(2), and one Si(3) atom. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Mg(3), one Mg(6), three equivalent Mg(1), three equivalent Mg(2), and one Si(2) atom. In the third Si site, Si(3) is bonded in a 10-coordinate geometry to one Mg(2), one Mg(6), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(5), one Si(1), and one Si(4) atom. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(3), one Mg(5), one Mg(6), three equivalent Mg(4), and one Si(3) atom.
Mg3Si2 crystallizes in the triclinic P-1 space group. There are six inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 5-coordinate geometry to two equivalent Si(1) and three equivalent Si(2) atoms. There is one shorter (2.83 Å) and one longer (2.89 Å) Mg(1)-Si(1) bond length. There are a spread of Mg(1)-Si(2) bond distances ranging from 2.75-3.05 Å. In the second Mg site, Mg(2) is bonded in a 5-coordinate geometry to one Si(3), two equivalent Si(1), and three equivalent Si(2) atoms. The Mg(2)-Si(3) bond length is 3.19 Å. There is one shorter (2.75 Å) and one longer (2.85 Å) Mg(2)-Si(1) bond length. There are a spread of Mg(2)-Si(2) bond distances ranging from 2.78-2.92 Å. In the third Mg site, Mg(3) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), one Si(4), and two equivalent Si(3) atoms. The Mg(3)-Si(1) bond length is 2.80 Å. The Mg(3)-Si(2) bond length is 2.97 Å. The Mg(3)-Si(4) bond length is 2.72 Å. There is one shorter (2.82 Å) and one longer (2.90 Å) Mg(3)-Si(3) bond length. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to two equivalent Si(3) and three equivalent Si(4) atoms. There is one shorter (2.85 Å) and one longer (2.88 Å) Mg(4)-Si(3) bond length. There are a spread of Mg(4)-Si(4) bond distances ranging from 2.76-2.89 Å. In the fifth Mg site, Mg(5) is bonded in a 3-coordinate geometry to one Si(1), one Si(4), and two equivalent Si(3) atoms. The Mg(5)-Si(1) bond length is 2.90 Å. The Mg(5)-Si(4) bond length is 2.76 Å. There is one shorter (2.92 Å) and one longer (3.09 Å) Mg(5)-Si(3) bond length. In the sixth Mg site, Mg(6) is bonded in a 4-coordinate geometry to one Si(1), one Si(2), one Si(3), and one Si(4) atom. The Mg(6)-Si(1) bond length is 2.82 Å. The Mg(6)-Si(2) bond length is 2.79 Å. The Mg(6)-Si(3) bond length is 2.90 Å. The Mg(6)-Si(4) bond length is 2.81 Å. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(5), one Mg(6), two equivalent Mg(1), two equivalent Mg(2), and one Si(3) atom. The Si(1)-Si(3) bond length is 2.46 Å. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Mg(3), one Mg(6), three equivalent Mg(1), three equivalent Mg(2), and one Si(2) atom. The Si(2)-Si(2) bond length is 2.42 Å. In the third Si site, Si(3) is bonded in a 10-coordinate geometry to one Mg(2), one Mg(6), two equivalent Mg(3), two equivalent Mg(4), two equivalent Mg(5), one Si(1), and one Si(4) atom. The Si(3)-Si(4) bond length is 2.49 Å. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(3), one Mg(5), one Mg(6), three equivalent Mg(4), and one Si(3) atom.