Mg4Si3 crystallizes in the triclinic P1 space group. There are eight inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 1-coordinate geometry to one Mg(8), one Si(1), one Si(2), one Si(4), and one Si(5) atom. In the second Mg site, Mg(2) is bonded in a distorted single-bond geometry to one Si(4) and one Si(5) atom. In the third Mg site, Mg(3) is bonded in a 3-coordinate geometry to one Mg(8), one Si(2), and one Si(5) atom. In the fourth Mg site, Mg(4) is bonded in a 3-coordinate geometry to one Si(1), one Si(3), one Si(5), and one Si(6) atom. In the fifth Mg site, Mg(5) is bonded in a 1-coordinate geometry to one Mg(8) and one Si(1) atom. In the sixth Mg site, Mg(6) is bonded in a distorted single-bond geometry to one Si(4) atom. In the seventh Mg site, Mg(7) is bonded in a 1-coordinate geometry to one Mg(8), one Si(1), and one Si(2) atom. In the eighth Mg site, Mg(8) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(3), one Mg(5), one Mg(7), one Si(2), one Si(3), and one Si(6) atom. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(4), one Mg(5), one Mg(7), and one Si(5) atom. In the second Si site, Si(2) is bonded in a 3-coordinate geometry to one Mg(1), one Mg(3), one Mg(7), and one Mg(8) atom. In the third Si site, Si(3) is bonded in a 1-coordinate geometry to one Mg(4) and one Mg(8) atom. In the fourth Si site, Si(4) is bonded in a 3-coordinate geometry to one Mg(1), one Mg(2), and one Mg(6) atom. In the fifth Si site, Si(5) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(2), one Mg(3), one Mg(4), and one Si(1) atom. In the sixth Si site, Si(6) is bonded in a 1-coordinate geometry to one Mg(4) and one Mg(8) atom.
Mg4Si3 crystallizes in the triclinic P1 space group. There are eight inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 1-coordinate geometry to one Mg(8), one Si(1), one Si(2), one Si(4), and one Si(5) atom. The Mg(1)-Mg(8) bond length is 3.17 Å. The Mg(1)-Si(1) bond length is 2.98 Å. The Mg(1)-Si(2) bond length is 2.55 Å. The Mg(1)-Si(4) bond length is 1.83 Å. The Mg(1)-Si(5) bond length is 3.10 Å. In the second Mg site, Mg(2) is bonded in a distorted single-bond geometry to one Si(4) and one Si(5) atom. The Mg(2)-Si(4) bond length is 2.51 Å. The Mg(2)-Si(5) bond length is 3.19 Å. In the third Mg site, Mg(3) is bonded in a 3-coordinate geometry to one Mg(8), one Si(2), and one Si(5) atom. The Mg(3)-Mg(8) bond length is 2.11 Å. The Mg(3)-Si(2) bond length is 2.52 Å. The Mg(3)-Si(5) bond length is 2.78 Å. In the fourth Mg site, Mg(4) is bonded in a 3-coordinate geometry to one Si(1), one Si(3), one Si(5), and one Si(6) atom. The Mg(4)-Si(1) bond length is 2.88 Å. The Mg(4)-Si(3) bond length is 1.94 Å. The Mg(4)-Si(5) bond length is 2.37 Å. The Mg(4)-Si(6) bond length is 2.33 Å. In the fifth Mg site, Mg(5) is bonded in a 1-coordinate geometry to one Mg(8) and one Si(1) atom. The Mg(5)-Mg(8) bond length is 2.38 Å. The Mg(5)-Si(1) bond length is 2.49 Å. In the sixth Mg site, Mg(6) is bonded in a distorted single-bond geometry to one Si(4) atom. The Mg(6)-Si(4) bond length is 2.09 Å. In the seventh Mg site, Mg(7) is bonded in a 1-coordinate geometry to one Mg(8), one Si(1), and one Si(2) atom. The Mg(7)-Mg(8) bond length is 2.96 Å. The Mg(7)-Si(1) bond length is 2.86 Å. The Mg(7)-Si(2) bond length is 2.11 Å. In the eighth Mg site, Mg(8) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(3), one Mg(5), one Mg(7), one Si(2), one Si(3), and one Si(6) atom. The Mg(8)-Si(2) bond length is 3.08 Å. The Mg(8)-Si(3) bond length is 2.84 Å. The Mg(8)-Si(6) bond length is 3.21 Å. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(4), one Mg(5), one Mg(7), and one Si(5) atom. The Si(1)-Si(5) bond length is 2.07 Å. In the second Si site, Si(2) is bonded in a 3-coordinate geometry to one Mg(1), one Mg(3), one Mg(7), and one Mg(8) atom. In the third Si site, Si(3) is bonded in a 1-coordinate geometry to one Mg(4) and one Mg(8) atom. In the fourth Si site, Si(4) is bonded in a 3-coordinate geometry to one Mg(1), one Mg(2), and one Mg(6) atom. In the fifth Si site, Si(5) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(2), one Mg(3), one Mg(4), and one Si(1) atom. In the sixth Si site, Si(6) is bonded in a 1-coordinate geometry to one Mg(4) and one Mg(8) atom.