Mg2Si3 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 4-coordinate geometry to two equivalent Si(3) and two equivalent Si(6) atoms. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to three equivalent Si(4) and three equivalent Si(5) atoms. In the third Mg site, Mg(3) is bonded in a 3-coordinate geometry to one Si(3), one Si(4), two equivalent Si(1), and two equivalent Si(2) atoms. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Si(2), one Si(3), one Si(5), and two equivalent Si(1) atoms. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to two equivalent Mg(3), two equivalent Mg(4), one Si(2), one Si(3), and one Si(6) atom. In the second Si site, Si(2) is bonded in a 6-coordinate geometry to one Mg(4), two equivalent Mg(3), one Si(1), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a 7-coordinate geometry to one Mg(3), one Mg(4), two equivalent Mg(1), one Si(1), and two equivalent Si(6) atoms. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(3), three equivalent Mg(2), one Si(5), and two equivalent Si(2) atoms. In the fifth Si site, Si(5) is bonded in a 6-coordinate geometry to one Mg(4), three equivalent Mg(2), one Si(4), and one Si(5) atom. In the sixth Si site, Si(6) is bonded in a 2-coordinate geometry to two equivalent Mg(1), one Si(1), and two equivalent Si(3) atoms.
Mg2Si3 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 4-coordinate geometry to two equivalent Si(3) and two equivalent Si(6) atoms. There is one shorter (2.81 Å) and one longer (2.87 Å) Mg(1)-Si(3) bond length. There is one shorter (2.80 Å) and one longer (2.86 Å) Mg(1)-Si(6) bond length. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to three equivalent Si(4) and three equivalent Si(5) atoms. There are a spread of Mg(2)-Si(4) bond distances ranging from 2.67-3.17 Å. There are a spread of Mg(2)-Si(5) bond distances ranging from 2.69-2.80 Å. In the third Mg site, Mg(3) is bonded in a 3-coordinate geometry to one Si(3), one Si(4), two equivalent Si(1), and two equivalent Si(2) atoms. The Mg(3)-Si(3) bond length is 2.69 Å. The Mg(3)-Si(4) bond length is 3.16 Å. There is one shorter (2.63 Å) and one longer (3.03 Å) Mg(3)-Si(1) bond length. There is one shorter (2.69 Å) and one longer (2.91 Å) Mg(3)-Si(2) bond length. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Si(2), one Si(3), one Si(5), and two equivalent Si(1) atoms. The Mg(4)-Si(2) bond length is 2.71 Å. The Mg(4)-Si(3) bond length is 2.91 Å. The Mg(4)-Si(5) bond length is 2.70 Å. There is one shorter (2.71 Å) and one longer (2.81 Å) Mg(4)-Si(1) bond length. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to two equivalent Mg(3), two equivalent Mg(4), one Si(2), one Si(3), and one Si(6) atom. The Si(1)-Si(2) bond length is 2.51 Å. The Si(1)-Si(3) bond length is 2.68 Å. The Si(1)-Si(6) bond length is 2.42 Å. In the second Si site, Si(2) is bonded in a 6-coordinate geometry to one Mg(4), two equivalent Mg(3), one Si(1), and two equivalent Si(4) atoms. There is one shorter (2.37 Å) and one longer (2.41 Å) Si(2)-Si(4) bond length. In the third Si site, Si(3) is bonded in a 7-coordinate geometry to one Mg(3), one Mg(4), two equivalent Mg(1), one Si(1), and two equivalent Si(6) atoms. There is one shorter (2.46 Å) and one longer (2.50 Å) Si(3)-Si(6) bond length. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(3), three equivalent Mg(2), one Si(5), and two equivalent Si(2) atoms. The Si(4)-Si(5) bond length is 2.35 Å. In the fifth Si site, Si(5) is bonded in a 6-coordinate geometry to one Mg(4), three equivalent Mg(2), one Si(4), and one Si(5) atom. The Si(5)-Si(5) bond length is 2.39 Å. In the sixth Si site, Si(6) is bonded in a 2-coordinate geometry to two equivalent Mg(1), one Si(1), and two equivalent Si(3) atoms.