Mg2Si crystallizes in the triclinic P-1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 3-coordinate geometry to one Si(1) and two equivalent Si(2) atoms. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to one Si(2) and three equivalent Si(1) atoms. In the third Mg site, Mg(3) is bonded in a 3-coordinate geometry to one Si(2) and two equivalent Si(1) atoms. In the fourth Mg site, Mg(4) is bonded in a 4-coordinate geometry to one Si(1) and three equivalent Si(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(4), two equivalent Mg(3), three equivalent Mg(2), and one Si(2) atom. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(3), two equivalent Mg(1), three equivalent Mg(4), and one Si(1) atom.
Mg2Si crystallizes in the triclinic P-1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 3-coordinate geometry to one Si(1) and two equivalent Si(2) atoms. The Mg(1)-Si(1) bond length is 2.74 Å. There is one shorter (2.69 Å) and one longer (2.71 Å) Mg(1)-Si(2) bond length. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to one Si(2) and three equivalent Si(1) atoms. The Mg(2)-Si(2) bond length is 2.82 Å. There are a spread of Mg(2)-Si(1) bond distances ranging from 2.85-2.95 Å. In the third Mg site, Mg(3) is bonded in a 3-coordinate geometry to one Si(2) and two equivalent Si(1) atoms. The Mg(3)-Si(2) bond length is 2.89 Å. There is one shorter (2.79 Å) and one longer (2.82 Å) Mg(3)-Si(1) bond length. In the fourth Mg site, Mg(4) is bonded in a 4-coordinate geometry to one Si(1) and three equivalent Si(2) atoms. The Mg(4)-Si(1) bond length is 2.74 Å. There are a spread of Mg(4)-Si(2) bond distances ranging from 2.72-2.83 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(4), two equivalent Mg(3), three equivalent Mg(2), and one Si(2) atom. The Si(1)-Si(2) bond length is 2.50 Å. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(3), two equivalent Mg(1), three equivalent Mg(4), and one Si(1) atom.