Mg2Si3 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 5-coordinate geometry to one Mg(2), one Si(1), two equivalent Si(2), and two equivalent Si(3) atoms. In the second Mg site, Mg(2) is bonded in a 9-coordinate geometry to one Mg(1), two equivalent Mg(2), one Si(3), two equivalent Si(2), and three equivalent Si(1) atoms. There are three 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(3) atoms. In the second Si site, Si(2) is bonded in a 6-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), one Si(2), and one Si(3) atom. In the third Si site, Si(3) is bonded in a 6-coordinate geometry to one Mg(2), two equivalent Mg(1), one Si(2), and two equivalent Si(1) atoms.
Mg2Si3 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 5-coordinate geometry to one Mg(2), one Si(1), two equivalent Si(2), and two equivalent Si(3) atoms. The Mg(1)-Mg(2) bond length is 3.08 Å. The Mg(1)-Si(1) bond length is 2.80 Å. There is one shorter (2.68 Å) and one longer (2.73 Å) Mg(1)-Si(2) bond length. There is one shorter (2.90 Å) and one longer (2.98 Å) Mg(1)-Si(3) bond length. In the second Mg site, Mg(2) is bonded in a 9-coordinate geometry to one Mg(1), two equivalent Mg(2), one Si(3), two equivalent Si(2), and three equivalent Si(1) atoms. There is one shorter (2.97 Å) and one longer (2.99 Å) Mg(2)-Mg(2) bond length. The Mg(2)-Si(3) bond length is 3.06 Å. There is one shorter (2.63 Å) and one longer (2.74 Å) Mg(2)-Si(2) bond length. There are a spread of Mg(2)-Si(1) bond distances ranging from 2.71-3.06 Å. There are three 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(3) atoms. The Si(1)-Si(1) bond length is 2.47 Å. There is one shorter (2.45 Å) and one longer (2.51 Å) Si(1)-Si(3) bond length. In the second Si site, Si(2) is bonded in a 6-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), one Si(2), and one Si(3) atom. The Si(2)-Si(2) bond length is 2.36 Å. The Si(2)-Si(3) bond length is 2.41 Å. In the third Si site, Si(3) is bonded in a 6-coordinate geometry to one Mg(2), two equivalent Mg(1), one Si(2), and two equivalent Si(1) atoms.