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 6-coordinate geometry to one Si(1), two equivalent Si(2), two equivalent Si(3), and three equivalent Si(6) atoms. In the second Mg site, Mg(2) is bonded in a 8-coordinate geometry to one Si(6), two equivalent Si(2), and five equivalent Si(1) atoms. In the third Mg site, Mg(3) is bonded in a 7-coordinate geometry to one Mg(4), two equivalent Si(5), two equivalent Si(6), and three equivalent Si(3) atoms. In the fourth Mg site, Mg(4) is bonded in a 12-coordinate geometry to one Mg(3), one Mg(4), two equivalent Si(3), three equivalent Si(5), and five equivalent Si(4) atoms. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to one Mg(1), five equivalent Mg(2), one Si(1), and two equivalent Si(2) atoms. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Si(1), and two equivalent Si(6) atoms. In the third Si site, Si(3) is bonded in a 10-coordinate geometry to two equivalent Mg(1), two equivalent Mg(4), three equivalent Mg(3), one Si(6), and two equivalent Si(5) atoms. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to five equivalent Mg(4), two equivalent Si(4), and two equivalent Si(5) atoms. In the fifth Si site, Si(5) is bonded in a 9-coordinate geometry to two equivalent Mg(3), three equivalent Mg(4), two equivalent Si(3), and two equivalent Si(4) atoms. In the sixth Si site, Si(6) is bonded in a 9-coordinate geometry to one Mg(2), two equivalent Mg(3), three equivalent Mg(1), one Si(3), and two equivalent Si(2) 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 6-coordinate geometry to one Si(1), two equivalent Si(2), two equivalent Si(3), and three equivalent Si(6) atoms. The Mg(1)-Si(1) bond length is 2.86 Å. There is one shorter (2.85 Å) and one longer (2.88 Å) Mg(1)-Si(2) bond length. There is one shorter (3.23 Å) and one longer (3.24 Å) Mg(1)-Si(3) bond length. There are a spread of Mg(1)-Si(6) bond distances ranging from 2.72-2.92 Å. In the second Mg site, Mg(2) is bonded in a 8-coordinate geometry to one Si(6), two equivalent Si(2), and five equivalent Si(1) atoms. The Mg(2)-Si(6) bond length is 2.93 Å. There is one shorter (2.87 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 2.79-2.89 Å. In the third Mg site, Mg(3) is bonded in a 7-coordinate geometry to one Mg(4), two equivalent Si(5), two equivalent Si(6), and three equivalent Si(3) atoms. The Mg(3)-Mg(4) bond length is 3.01 Å. There is one shorter (2.84 Å) and one longer (2.87 Å) Mg(3)-Si(5) bond length. There is one shorter (2.71 Å) and one longer (2.73 Å) Mg(3)-Si(6) bond length. There are a spread of Mg(3)-Si(3) bond distances ranging from 2.80-2.94 Å. In the fourth Mg site, Mg(4) is bonded in a 12-coordinate geometry to one Mg(3), one Mg(4), two equivalent Si(3), three equivalent Si(5), and five equivalent Si(4) atoms. The Mg(4)-Mg(4) bond length is 3.09 Å. There is one shorter (3.13 Å) and one longer (3.14 Å) Mg(4)-Si(3) bond length. There are a spread of Mg(4)-Si(5) bond distances ranging from 2.82-3.18 Å. There are a spread of Mg(4)-Si(4) bond distances ranging from 2.80-3.13 Å. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to one Mg(1), five equivalent Mg(2), one Si(1), and two equivalent Si(2) atoms. The Si(1)-Si(1) bond length is 2.54 Å. Both Si(1)-Si(2) bond lengths are 2.50 Å. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), two equivalent Si(1), and two equivalent Si(6) atoms. Both Si(2)-Si(6) bond lengths are 2.54 Å. In the third Si site, Si(3) is bonded in a 10-coordinate geometry to two equivalent Mg(1), two equivalent Mg(4), three equivalent Mg(3), one Si(6), and two equivalent Si(5) atoms. The Si(3)-Si(6) bond length is 2.57 Å. There is one shorter (2.52 Å) and one longer (2.53 Å) Si(3)-Si(5) bond length. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to five equivalent Mg(4), two equivalent Si(4), and two equivalent Si(5) atoms. Both Si(4)-Si(4) bond lengths are 2.61 Å. There is one shorter (2.58 Å) and one longer (2.61 Å) Si(4)-Si(5) bond length. In the fifth Si site, Si(5) is bonded in a 9-coordinate geometry to two equivalent Mg(3), three equivalent Mg(4), two equivalent Si(3), and two equivalent Si(4) atoms. In the sixth Si site, Si(6) is bonded in a 9-coordinate geometry to one Mg(2), two equivalent Mg(3), three equivalent Mg(1), one Si(3), and two equivalent Si(2) atoms.