Mg5Si6 is Magnesium tetraboride-like structured and crystallizes in the triclinic P1 space group. There are ten inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 5-coordinate geometry to one Si(1), one Si(11), one Si(2), one Si(5), and one Si(6) atom. In the second Mg site, Mg(2) is bonded in a 5-coordinate geometry to one Si(11), one Si(3), one Si(6), one Si(7), and one Si(8) atom. In the third Mg site, Mg(3) is bonded in a 4-coordinate geometry to one Si(3), one Si(4), one Si(5), and one Si(8) atom. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Si(10), one Si(3), one Si(4), one Si(7), and one Si(8) atom. In the fifth Mg site, Mg(5) is bonded in a 5-coordinate geometry to one Si(11), one Si(6), one Si(7), and two equivalent Si(2) atoms. In the sixth Mg site, Mg(6) is bonded in a 7-coordinate geometry to one Si(1), one Si(4), one Si(8), two equivalent Si(5), and two equivalent Si(9) atoms. In the seventh Mg site, Mg(7) is bonded in a 5-coordinate geometry to one Si(12), one Si(3), one Si(4), one Si(5), and one Si(8) atom. In the eighth Mg site, Mg(8) is bonded in a 5-coordinate geometry to one Si(10), one Si(11), one Si(2), one Si(3), one Si(6), and one Si(7) atom. In the ninth Mg site, Mg(9) is bonded in a 6-coordinate geometry to one Si(11), one Si(2), one Si(6), one Si(9), and two equivalent Si(1) atoms. In the tenth Mg site, Mg(10) is bonded in a 6-coordinate geometry to one Si(1), one Si(2), one Si(5), one Si(9), and two equivalent Si(12) atoms. There are twelve inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(10), one Mg(6), two equivalent Mg(9), one Si(12), one Si(2), and one Si(9) atom. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(10), one Mg(8), one Mg(9), two equivalent Mg(5), one Si(1), and one Si(10) atom. In the third Si site, Si(3) is bonded in a 6-coordinate geometry to one Mg(2), one Mg(3), one Mg(4), one Mg(7), one Mg(8), and one Si(7) atom. In the fourth Si site, Si(4) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(4), one Mg(6), one Mg(7), one Si(12), one Si(9), and two equivalent Si(8) atoms. In the fifth Si site, Si(5) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(10), one Mg(3), one Mg(7), two equivalent Mg(6), one Si(12), and one Si(9) atom. In the sixth Si site, Si(6) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(2), one Mg(5), one Mg(8), one Mg(9), one Si(10), and two equivalent Si(11) atoms. In the seventh Si site, Si(7) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(4), one Mg(5), one Mg(8), one Si(11), one Si(3), and two equivalent Si(10) atoms. In the eighth Si site, Si(8) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(3), one Mg(4), one Mg(6), one Mg(7), one Si(9), and two equivalent Si(4) atoms. In the ninth Si site, Si(9) is bonded in a 9-coordinate geometry to one Mg(10), one Mg(9), two equivalent Mg(6), one Si(1), one Si(12), one Si(4), one Si(5), and one Si(8) atom. In the tenth Si site, Si(10) is bonded in a 5-coordinate geometry to one Mg(4), one Mg(8), one Si(2), one Si(6), and two equivalent Si(7) atoms. In the eleventh Si site, Si(11) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(2), one Mg(5), one Mg(8), one Mg(9), one Si(7), and two equivalent Si(6) atoms. In the twelfth Si site, Si(12) is bonded in a 7-coordinate geometry to one Mg(7), two equivalent Mg(10), one Si(1), one Si(4), one Si(5), and one Si(9) atom.
Mg5Si6 is Magnesium tetraboride-like structured and crystallizes in the triclinic P1 space group. There are ten inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 5-coordinate geometry to one Si(1), one Si(11), one Si(2), one Si(5), and one Si(6) atom. The Mg(1)-Si(1) bond length is 2.98 Å. The Mg(1)-Si(11) bond length is 2.86 Å. The Mg(1)-Si(2) bond length is 2.73 Å. The Mg(1)-Si(5) bond length is 2.81 Å. The Mg(1)-Si(6) bond length is 2.77 Å. In the second Mg site, Mg(2) is bonded in a 5-coordinate geometry to one Si(11), one Si(3), one Si(6), one Si(7), and one Si(8) atom. The Mg(2)-Si(11) bond length is 2.72 Å. The Mg(2)-Si(3) bond length is 2.73 Å. The Mg(2)-Si(6) bond length is 2.88 Å. The Mg(2)-Si(7) bond length is 2.91 Å. The Mg(2)-Si(8) bond length is 2.69 Å. In the third Mg site, Mg(3) is bonded in a 4-coordinate geometry to one Si(3), one Si(4), one Si(5), and one Si(8) atom. The Mg(3)-Si(3) bond length is 2.80 Å. The Mg(3)-Si(4) bond length is 2.85 Å. The Mg(3)-Si(5) bond length is 2.79 Å. The Mg(3)-Si(8) bond length is 2.82 Å. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Si(10), one Si(3), one Si(4), one Si(7), and one Si(8) atom. The Mg(4)-Si(10) bond length is 2.73 Å. The Mg(4)-Si(3) bond length is 3.02 Å. The Mg(4)-Si(4) bond length is 2.76 Å. The Mg(4)-Si(7) bond length is 2.87 Å. The Mg(4)-Si(8) bond length is 2.84 Å. In the fifth Mg site, Mg(5) is bonded in a 5-coordinate geometry to one Si(11), one Si(6), one Si(7), and two equivalent Si(2) atoms. The Mg(5)-Si(11) bond length is 2.91 Å. The Mg(5)-Si(6) bond length is 2.85 Å. The Mg(5)-Si(7) bond length is 2.72 Å. There is one shorter (2.75 Å) and one longer (2.94 Å) Mg(5)-Si(2) bond length. In the sixth Mg site, Mg(6) is bonded in a 7-coordinate geometry to one Si(1), one Si(4), one Si(8), two equivalent Si(5), and two equivalent Si(9) atoms. The Mg(6)-Si(1) bond length is 2.94 Å. The Mg(6)-Si(4) bond length is 2.89 Å. The Mg(6)-Si(8) bond length is 2.88 Å. There is one shorter (2.78 Å) and one longer (2.85 Å) Mg(6)-Si(5) bond length. There is one shorter (2.85 Å) and one longer (2.99 Å) Mg(6)-Si(9) bond length. In the seventh Mg site, Mg(7) is bonded in a 5-coordinate geometry to one Si(12), one Si(3), one Si(4), one Si(5), and one Si(8) atom. The Mg(7)-Si(12) bond length is 2.76 Å. The Mg(7)-Si(3) bond length is 2.73 Å. The Mg(7)-Si(4) bond length is 2.83 Å. The Mg(7)-Si(5) bond length is 2.82 Å. The Mg(7)-Si(8) bond length is 2.79 Å. In the eighth Mg site, Mg(8) is bonded in a 5-coordinate geometry to one Si(10), one Si(11), one Si(2), one Si(3), one Si(6), and one Si(7) atom. The Mg(8)-Si(10) bond length is 2.84 Å. The Mg(8)-Si(11) bond length is 3.03 Å. The Mg(8)-Si(2) bond length is 3.19 Å. The Mg(8)-Si(3) bond length is 2.87 Å. The Mg(8)-Si(6) bond length is 2.71 Å. The Mg(8)-Si(7) bond length is 3.04 Å. In the ninth Mg site, Mg(9) is bonded in a 6-coordinate geometry to one Si(11), one Si(2), one Si(6), one Si(9), and two equivalent Si(1) atoms. The Mg(9)-Si(11) bond length is 2.87 Å. The Mg(9)-Si(2) bond length is 2.97 Å. The Mg(9)-Si(6) bond length is 2.68 Å. The Mg(9)-Si(9) bond length is 2.99 Å. There is one shorter (2.71 Å) and one longer (2.99 Å) Mg(9)-Si(1) bond length. In the tenth Mg site, Mg(10) is bonded in a 6-coordinate geometry to one Si(1), one Si(2), one Si(5), one Si(9), and two equivalent Si(12) atoms. The Mg(10)-Si(1) bond length is 2.85 Å. The Mg(10)-Si(2) bond length is 2.88 Å. The Mg(10)-Si(5) bond length is 2.71 Å. The Mg(10)-Si(9) bond length is 2.95 Å. There is one shorter (2.83 Å) and one longer (2.95 Å) Mg(10)-Si(12) bond length. There are twelve inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(10), one Mg(6), two equivalent Mg(9), one Si(12), one Si(2), and one Si(9) atom. The Si(1)-Si(12) bond length is 2.54 Å. The Si(1)-Si(2) bond length is 2.38 Å. The Si(1)-Si(9) bond length is 2.55 Å. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(10), one Mg(8), one Mg(9), two equivalent Mg(5), one Si(1), and one Si(10) atom. The Si(2)-Si(10) bond length is 2.42 Å. In the third Si site, Si(3) is bonded in a 6-coordinate geometry to one Mg(2), one Mg(3), one Mg(4), one Mg(7), one Mg(8), and one Si(7) atom. The Si(3)-Si(7) bond length is 2.46 Å. In the fourth Si site, Si(4) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(4), one Mg(6), one Mg(7), one Si(12), one Si(9), and two equivalent Si(8) atoms. The Si(4)-Si(12) bond length is 2.51 Å. The Si(4)-Si(9) bond length is 2.49 Å. There is one shorter (2.50 Å) and one longer (2.78 Å) Si(4)-Si(8) bond length. In the fifth Si site, Si(5) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(10), one Mg(3), one Mg(7), two equivalent Mg(6), one Si(12), and one Si(9) atom. The Si(5)-Si(12) bond length is 2.47 Å. The Si(5)-Si(9) bond length is 2.58 Å. In the sixth Si site, Si(6) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(2), one Mg(5), one Mg(8), one Mg(9), one Si(10), and two equivalent Si(11) atoms. The Si(6)-Si(10) bond length is 2.38 Å. There is one shorter (2.51 Å) and one longer (2.67 Å) Si(6)-Si(11) bond length. In the seventh Si site, Si(7) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(4), one Mg(5), one Mg(8), one Si(11), one Si(3), and two equivalent Si(10) atoms. The Si(7)-Si(11) bond length is 2.45 Å. There is one shorter (2.54 Å) and one longer (2.75 Å) Si(7)-Si(10) bond length. In the eighth Si site, Si(8) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(3), one Mg(4), one Mg(6), one Mg(7), one Si(9), and two equivalent Si(4) atoms. The Si(8)-Si(9) bond length is 2.60 Å. In the ninth Si site, Si(9) is bonded in a 9-coordinate geometry to one Mg(10), one Mg(9), two equivalent Mg(6), one Si(1), one Si(12), one Si(4), one Si(5), and one Si(8) atom. The Si(9)-Si(12) bond length is 2.50 Å. In the tenth Si site, Si(10) is bonded in a 5-coordinate geometry to one Mg(4), one Mg(8), one Si(2), one Si(6), and two equivalent Si(7) atoms. In the eleventh Si site, Si(11) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(2), one Mg(5), one Mg(8), one Mg(9), one Si(7), and two equivalent Si(6) atoms. In the twelfth Si site, Si(12) is bonded in a 7-coordinate geometry to one Mg(7), two equivalent Mg(10), one Si(1), one Si(4), one Si(5), and one Si(9) atom.