Mg3Si4 is Magnesium tetraboride-like structured and crystallizes in the triclinic P1 space group. There are six inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 5-coordinate geometry to one Si(1), two equivalent Si(4), and two equivalent Si(7) atoms. In the second Mg site, Mg(2) is bonded in a 7-coordinate geometry to one Si(7), two equivalent Si(1), two equivalent Si(5), and two equivalent Si(8) atoms. In the third Mg site, Mg(3) is bonded in a 7-coordinate geometry to one Si(4), two equivalent Si(1), two equivalent Si(2), and two equivalent Si(5) atoms. In the fourth Mg site, Mg(4) is bonded in a 8-coordinate geometry to one Si(4), one Si(8), two equivalent Si(2), two equivalent Si(3), and two equivalent Si(7) atoms. In the fifth Mg site, Mg(5) is bonded in a 5-coordinate geometry to one Si(4), one Si(8), two equivalent Si(1), two equivalent Si(3), and two equivalent Si(6) atoms. In the sixth Mg site, Mg(6) is bonded in a 5-coordinate geometry to one Si(4), one Si(6), one Si(7), and two equivalent Si(5) atoms. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to one Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(5), and one Si(5) atom. In the second Si site, Si(2) is bonded in a 6-coordinate geometry to two equivalent Mg(3), two equivalent Mg(4), one Si(6), and one Si(7) atom. In the third Si site, Si(3) is bonded in a 7-coordinate geometry to two equivalent Mg(4), two equivalent Mg(5), one Si(6), and two equivalent Si(4) atoms. In the fourth Si site, Si(4) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(4), one Mg(5), one Mg(6), two equivalent Mg(1), and two equivalent Si(3) atoms. In the fifth Si site, Si(5) is bonded in a 8-coordinate geometry to two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(6), one Si(1), and one Si(8) atom. In the sixth Si site, Si(6) is bonded in a 7-coordinate geometry to one Mg(6), two equivalent Mg(5), one Si(2), one Si(3), and two equivalent Si(8) atoms. In the seventh Si site, Si(7) is bonded in a 7-coordinate geometry to one Mg(2), one Mg(6), two equivalent Mg(1), two equivalent Mg(4), and one Si(2) atom. In the eighth Si site, Si(8) is bonded in a 7-coordinate geometry to one Mg(4), one Mg(5), two equivalent Mg(2), one Si(5), and two equivalent Si(6) atoms.
Mg3Si4 is Magnesium tetraboride-like structured and crystallizes in the triclinic P1 space group. There are six inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 5-coordinate geometry to one Si(1), two equivalent Si(4), and two equivalent Si(7) atoms. The Mg(1)-Si(1) bond length is 2.68 Å. There is one shorter (3.03 Å) and one longer (3.09 Å) Mg(1)-Si(4) bond length. There is one shorter (2.82 Å) and one longer (2.89 Å) Mg(1)-Si(7) bond length. In the second Mg site, Mg(2) is bonded in a 7-coordinate geometry to one Si(7), two equivalent Si(1), two equivalent Si(5), and two equivalent Si(8) atoms. The Mg(2)-Si(7) bond length is 2.67 Å. There is one shorter (2.87 Å) and one longer (2.88 Å) Mg(2)-Si(1) bond length. There is one shorter (2.84 Å) and one longer (2.89 Å) Mg(2)-Si(5) bond length. There is one shorter (2.93 Å) and one longer (3.13 Å) Mg(2)-Si(8) bond length. In the third Mg site, Mg(3) is bonded in a 7-coordinate geometry to one Si(4), two equivalent Si(1), two equivalent Si(2), and two equivalent Si(5) atoms. The Mg(3)-Si(4) bond length is 2.74 Å. There is one shorter (2.85 Å) and one longer (2.91 Å) Mg(3)-Si(1) bond length. There is one shorter (2.85 Å) and one longer (2.89 Å) Mg(3)-Si(2) bond length. There is one shorter (2.96 Å) and one longer (2.97 Å) Mg(3)-Si(5) bond length. In the fourth Mg site, Mg(4) is bonded in a 8-coordinate geometry to one Si(4), one Si(8), two equivalent Si(2), two equivalent Si(3), and two equivalent Si(7) atoms. The Mg(4)-Si(4) bond length is 2.93 Å. The Mg(4)-Si(8) bond length is 2.93 Å. There is one shorter (3.00 Å) and one longer (3.04 Å) Mg(4)-Si(2) bond length. There is one shorter (2.93 Å) and one longer (3.01 Å) Mg(4)-Si(3) bond length. There is one shorter (2.75 Å) and one longer (2.79 Å) Mg(4)-Si(7) bond length. In the fifth Mg site, Mg(5) is bonded in a 5-coordinate geometry to one Si(4), one Si(8), two equivalent Si(1), two equivalent Si(3), and two equivalent Si(6) atoms. The Mg(5)-Si(4) bond length is 2.77 Å. The Mg(5)-Si(8) bond length is 3.13 Å. There is one shorter (2.69 Å) and one longer (2.70 Å) Mg(5)-Si(1) bond length. There is one shorter (2.98 Å) and one longer (3.03 Å) Mg(5)-Si(3) bond length. There is one shorter (2.82 Å) and one longer (2.86 Å) Mg(5)-Si(6) bond length. In the sixth Mg site, Mg(6) is bonded in a 5-coordinate geometry to one Si(4), one Si(6), one Si(7), and two equivalent Si(5) atoms. The Mg(6)-Si(4) bond length is 2.90 Å. The Mg(6)-Si(6) bond length is 3.03 Å. The Mg(6)-Si(7) bond length is 2.63 Å. There is one shorter (2.63 Å) and one longer (2.64 Å) Mg(6)-Si(5) bond length. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to one Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(5), and one Si(5) atom. The Si(1)-Si(5) bond length is 2.32 Å. In the second Si site, Si(2) is bonded in a 6-coordinate geometry to two equivalent Mg(3), two equivalent Mg(4), one Si(6), and one Si(7) atom. The Si(2)-Si(6) bond length is 2.42 Å. The Si(2)-Si(7) bond length is 2.41 Å. In the third Si site, Si(3) is bonded in a 7-coordinate geometry to two equivalent Mg(4), two equivalent Mg(5), one Si(6), and two equivalent Si(4) atoms. The Si(3)-Si(6) bond length is 2.46 Å. There is one shorter (2.45 Å) and one longer (2.46 Å) Si(3)-Si(4) bond length. In the fourth Si site, Si(4) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(4), one Mg(5), one Mg(6), two equivalent Mg(1), and two equivalent Si(3) atoms. In the fifth Si site, Si(5) is bonded in a 8-coordinate geometry to two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(6), one Si(1), and one Si(8) atom. The Si(5)-Si(8) bond length is 2.43 Å. In the sixth Si site, Si(6) is bonded in a 7-coordinate geometry to one Mg(6), two equivalent Mg(5), one Si(2), one Si(3), and two equivalent Si(8) atoms. There is one shorter (2.42 Å) and one longer (2.43 Å) Si(6)-Si(8) bond length. In the seventh Si site, Si(7) is bonded in a 7-coordinate geometry to one Mg(2), one Mg(6), two equivalent Mg(1), two equivalent Mg(4), and one Si(2) atom. In the eighth Si site, Si(8) is bonded in a 7-coordinate geometry to one Mg(4), one Mg(5), two equivalent Mg(2), one Si(5), and two equivalent Si(6) atoms.