Mg3Si4 crystallizes in the triclinic P-1 space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 6-coordinate geometry to two equivalent Si(1), two equivalent Si(3), and two equivalent Si(4) atoms. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one Si(1), two equivalent Si(2), two equivalent Si(3), and two equivalent Si(4) atoms. In the third Mg site, Mg(3) is bonded in a 7-coordinate geometry to one Si(1), one Si(3), two equivalent Si(2), and three equivalent Si(4) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to one Mg(2), one Mg(3), two equivalent Mg(1), one Si(1), one Si(2), and one Si(3) atom. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to two equivalent Mg(2), two equivalent Mg(3), one Si(1), one Si(3), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(3), two equivalent Mg(1), two equivalent Mg(2), one Si(1), one Si(2), and one Si(4) atom. In the fourth Si site, Si(4) is bonded in a 10-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), three equivalent Mg(3), one Si(3), and two equivalent Si(2) atoms.
Mg3Si4 crystallizes in the triclinic P-1 space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 6-coordinate geometry to two equivalent Si(1), two equivalent Si(3), and two equivalent Si(4) atoms. There is one shorter (2.73 Å) and one longer (2.93 Å) Mg(1)-Si(1) bond length. There is one shorter (2.77 Å) and one longer (2.82 Å) Mg(1)-Si(3) bond length. There is one shorter (2.88 Å) and one longer (3.09 Å) Mg(1)-Si(4) bond length. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one Si(1), two equivalent Si(2), two equivalent Si(3), and two equivalent Si(4) atoms. The Mg(2)-Si(1) bond length is 2.91 Å. There is one shorter (2.75 Å) and one longer (3.21 Å) Mg(2)-Si(2) bond length. There is one shorter (2.81 Å) and one longer (2.94 Å) Mg(2)-Si(3) bond length. There is one shorter (2.82 Å) and one longer (2.93 Å) Mg(2)-Si(4) bond length. In the third Mg site, Mg(3) is bonded in a 7-coordinate geometry to one Si(1), one Si(3), two equivalent Si(2), and three equivalent Si(4) atoms. The Mg(3)-Si(1) bond length is 2.87 Å. The Mg(3)-Si(3) bond length is 2.88 Å. There is one shorter (2.95 Å) and one longer (2.96 Å) Mg(3)-Si(2) bond length. There are a spread of Mg(3)-Si(4) bond distances ranging from 2.78-3.00 Å. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to one Mg(2), one Mg(3), two equivalent Mg(1), one Si(1), one Si(2), and one Si(3) atom. The Si(1)-Si(1) bond length is 2.43 Å. The Si(1)-Si(2) bond length is 2.59 Å. The Si(1)-Si(3) bond length is 2.64 Å. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to two equivalent Mg(2), two equivalent Mg(3), one Si(1), one Si(3), and two equivalent Si(4) atoms. The Si(2)-Si(3) bond length is 2.56 Å. There is one shorter (2.53 Å) and one longer (2.60 Å) Si(2)-Si(4) bond length. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(3), two equivalent Mg(1), two equivalent Mg(2), one Si(1), one Si(2), and one Si(4) atom. The Si(3)-Si(4) bond length is 2.50 Å. In the fourth Si site, Si(4) is bonded in a 10-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), three equivalent Mg(3), one Si(3), and two equivalent Si(2) atoms.