Mg4Si3 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 6-coordinate geometry to one Si(3), two equivalent Si(1), and three equivalent Si(2) atoms. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one Si(3), two equivalent Si(2), and three equivalent Si(1) atoms. In the third Mg site, Mg(3) is bonded in a 5-coordinate geometry to one Si(2), two equivalent Si(1), and two equivalent Si(3) atoms. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), and three equivalent Si(3) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to one Mg(4), two equivalent Mg(1), two equivalent Mg(3), three equivalent Mg(2), and one Si(2) atom. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Mg(3), one Mg(4), two equivalent Mg(2), three equivalent Mg(1), one Si(1), and one Si(2) atom. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(2), two equivalent Mg(3), three equivalent Mg(4), and one Si(3) atom.
Mg4Si3 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 6-coordinate geometry to one Si(3), two equivalent Si(1), and three equivalent Si(2) atoms. The Mg(1)-Si(3) bond length is 2.69 Å. There is one shorter (2.72 Å) and one longer (3.00 Å) Mg(1)-Si(1) bond length. There are a spread of Mg(1)-Si(2) bond distances ranging from 2.83-2.94 Å. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one Si(3), two equivalent Si(2), and three equivalent Si(1) atoms. The Mg(2)-Si(3) bond length is 2.85 Å. There is one shorter (2.89 Å) and one longer (2.90 Å) Mg(2)-Si(2) bond length. There are a spread of Mg(2)-Si(1) bond distances ranging from 2.83-3.11 Å. In the third Mg site, Mg(3) is bonded in a 5-coordinate geometry to one Si(2), two equivalent Si(1), and two equivalent Si(3) atoms. The Mg(3)-Si(2) bond length is 2.81 Å. There is one shorter (2.87 Å) and one longer (3.03 Å) Mg(3)-Si(1) bond length. There is one shorter (2.71 Å) and one longer (2.85 Å) Mg(3)-Si(3) bond length. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), and three equivalent Si(3) atoms. The Mg(4)-Si(1) bond length is 2.66 Å. The Mg(4)-Si(2) bond length is 2.64 Å. There are a spread of Mg(4)-Si(3) bond distances ranging from 2.79-2.92 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to one Mg(4), two equivalent Mg(1), two equivalent Mg(3), three equivalent Mg(2), and one Si(2) atom. The Si(1)-Si(2) bond length is 2.41 Å. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Mg(3), one Mg(4), two equivalent Mg(2), three equivalent Mg(1), one Si(1), and one Si(2) atom. The Si(2)-Si(2) bond length is 2.38 Å. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(2), two equivalent Mg(3), three equivalent Mg(4), and one Si(3) atom. The Si(3)-Si(3) bond length is 2.47 Å.