Mg6Si5 is Magnesium tetraboride-like structured and crystallizes in the triclinic P1 space group. There are twelve inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 3-coordinate geometry to one Si(9) and two equivalent Si(4) atoms. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one Si(1), one Si(6), one Si(7), two equivalent Si(2), and two equivalent Si(5) atoms. In the third Mg site, Mg(3) is bonded in a 6-coordinate geometry to one Si(10), one Si(2), one Si(7), two equivalent Si(3), and two equivalent Si(6) atoms. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), one Si(5), and two equivalent Si(8) atoms. In the fifth Mg site, Mg(5) is bonded in a 6-coordinate geometry to one Si(4), one Si(5), one Si(8), one Si(9), and two equivalent Si(1) atoms. In the sixth Mg site, Mg(6) is bonded in a 4-coordinate geometry to one Si(3), one Si(7), and two equivalent Si(10) atoms. In the seventh Mg site, Mg(7) is bonded in a 6-coordinate geometry to one Si(10), one Si(2), one Si(5), one Si(6), and two equivalent Si(7) atoms. In the eighth Mg site, Mg(8) is bonded in a 3-coordinate geometry to one Si(1), one Si(6), one Si(8), two equivalent Si(2), and two equivalent Si(5) atoms. In the ninth Mg site, Mg(9) is bonded in a 5-coordinate geometry to one Si(1), one Si(4), one Si(8), and two equivalent Si(9) atoms. In the tenth Mg site, Mg(10) is bonded in a distorted linear geometry to one Si(3) and one Si(9) atom. In the eleventh Mg site, Mg(11) is bonded in a 4-coordinate geometry to one Si(10), one Si(3), one Si(4), and one Si(9) atom. In the twelfth Mg site, Mg(12) is bonded in a 4-coordinate geometry to one Si(10), one Si(3), one Si(4), and one Si(9) atom. There are ten inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(4), one Mg(8), one Mg(9), two equivalent Mg(5), one Si(5), and one Si(8) atom. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Mg(3), one Mg(4), one Mg(7), two equivalent Mg(2), two equivalent Mg(8), one Si(6), and one Si(7) atom. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(10), one Mg(11), one Mg(12), one Mg(6), two equivalent Mg(3), one Si(10), and one Si(6) atom. In the fourth Si site, Si(4) is bonded in a 8-coordinate geometry to one Mg(11), one Mg(12), one Mg(5), one Mg(9), two equivalent Mg(1), one Si(8), and one Si(9) atom. In the fifth Si site, Si(5) is bonded in a 9-coordinate geometry to one Mg(4), one Mg(5), one Mg(7), two equivalent Mg(2), two equivalent Mg(8), one Si(1), and one Si(8) atom. In the sixth Si site, Si(6) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(7), one Mg(8), two equivalent Mg(3), one Si(2), one Si(3), and one Si(7) atom. In the seventh Si site, Si(7) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(3), one Mg(6), two equivalent Mg(7), one Si(10), one Si(2), and one Si(6) atom. In the eighth Si site, Si(8) is bonded in a 8-coordinate geometry to one Mg(5), one Mg(8), one Mg(9), two equivalent Mg(4), one Si(1), one Si(4), and one Si(5) atom. In the ninth Si site, Si(9) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(10), one Mg(11), one Mg(12), one Mg(5), two equivalent Mg(9), and one Si(4) atom. In the tenth Si site, Si(10) is bonded in a 8-coordinate geometry to one Mg(11), one Mg(12), one Mg(3), one Mg(7), two equivalent Mg(6), one Si(3), and one Si(7) atom.
Mg6Si5 is Magnesium tetraboride-like structured and crystallizes in the triclinic P1 space group. There are twelve inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 3-coordinate geometry to one Si(9) and two equivalent Si(4) atoms. The Mg(1)-Si(9) bond length is 2.84 Å. There is one shorter (2.79 Å) and one longer (2.83 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), one Si(6), one Si(7), two equivalent Si(2), and two equivalent Si(5) atoms. The Mg(2)-Si(1) bond length is 2.76 Å. The Mg(2)-Si(6) bond length is 2.91 Å. The Mg(2)-Si(7) bond length is 2.80 Å. There is one shorter (3.00 Å) and one longer (3.27 Å) Mg(2)-Si(2) bond length. There is one shorter (2.98 Å) and one longer (3.01 Å) Mg(2)-Si(5) bond length. In the third Mg site, Mg(3) is bonded in a 6-coordinate geometry to one Si(10), one Si(2), one Si(7), two equivalent Si(3), and two equivalent Si(6) atoms. The Mg(3)-Si(10) bond length is 3.03 Å. The Mg(3)-Si(2) bond length is 3.05 Å. The Mg(3)-Si(7) bond length is 3.07 Å. There is one shorter (2.79 Å) and one longer (3.19 Å) Mg(3)-Si(3) bond length. There is one shorter (2.78 Å) and one longer (3.03 Å) Mg(3)-Si(6) bond length. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), one Si(5), and two equivalent Si(8) atoms. The Mg(4)-Si(1) bond length is 2.87 Å. The Mg(4)-Si(2) bond length is 2.94 Å. The Mg(4)-Si(5) bond length is 2.93 Å. There is one shorter (2.78 Å) and one longer (2.79 Å) Mg(4)-Si(8) bond length. In the fifth Mg site, Mg(5) is bonded in a 6-coordinate geometry to one Si(4), one Si(5), one Si(8), one Si(9), and two equivalent Si(1) atoms. The Mg(5)-Si(4) bond length is 2.73 Å. The Mg(5)-Si(5) bond length is 2.86 Å. The Mg(5)-Si(8) bond length is 2.86 Å. The Mg(5)-Si(9) bond length is 2.72 Å. There is one shorter (2.71 Å) and one longer (2.89 Å) Mg(5)-Si(1) bond length. In the sixth Mg site, Mg(6) is bonded in a 4-coordinate geometry to one Si(3), one Si(7), and two equivalent Si(10) atoms. The Mg(6)-Si(3) bond length is 3.03 Å. The Mg(6)-Si(7) bond length is 2.76 Å. There is one shorter (2.79 Å) and one longer (2.91 Å) Mg(6)-Si(10) bond length. In the seventh Mg site, Mg(7) is bonded in a 6-coordinate geometry to one Si(10), one Si(2), one Si(5), one Si(6), and two equivalent Si(7) atoms. The Mg(7)-Si(10) bond length is 2.79 Å. The Mg(7)-Si(2) bond length is 2.90 Å. The Mg(7)-Si(5) bond length is 2.81 Å. The Mg(7)-Si(6) bond length is 2.85 Å. There is one shorter (2.76 Å) and one longer (2.89 Å) Mg(7)-Si(7) bond length. In the eighth Mg site, Mg(8) is bonded in a 3-coordinate geometry to one Si(1), one Si(6), one Si(8), two equivalent Si(2), and two equivalent Si(5) atoms. The Mg(8)-Si(1) bond length is 2.99 Å. The Mg(8)-Si(6) bond length is 2.78 Å. The Mg(8)-Si(8) bond length is 2.77 Å. There is one shorter (2.88 Å) and one longer (3.18 Å) Mg(8)-Si(2) bond length. Both Mg(8)-Si(5) bond lengths are 3.14 Å. In the ninth Mg site, Mg(9) is bonded in a 5-coordinate geometry to one Si(1), one Si(4), one Si(8), and two equivalent Si(9) atoms. The Mg(9)-Si(1) bond length is 2.75 Å. The Mg(9)-Si(4) bond length is 2.81 Å. The Mg(9)-Si(8) bond length is 2.80 Å. There is one shorter (2.71 Å) and one longer (2.86 Å) Mg(9)-Si(9) bond length. In the tenth Mg site, Mg(10) is bonded in a distorted linear geometry to one Si(3) and one Si(9) atom. The Mg(10)-Si(3) bond length is 2.76 Å. The Mg(10)-Si(9) bond length is 2.77 Å. In the eleventh Mg site, Mg(11) is bonded in a 4-coordinate geometry to one Si(10), one Si(3), one Si(4), and one Si(9) atom. The Mg(11)-Si(10) bond length is 3.04 Å. The Mg(11)-Si(3) bond length is 2.86 Å. The Mg(11)-Si(4) bond length is 2.73 Å. The Mg(11)-Si(9) bond length is 2.74 Å. In the twelfth Mg site, Mg(12) is bonded in a 4-coordinate geometry to one Si(10), one Si(3), one Si(4), and one Si(9) atom. The Mg(12)-Si(10) bond length is 2.79 Å. The Mg(12)-Si(3) bond length is 2.69 Å. The Mg(12)-Si(4) bond length is 2.83 Å. The Mg(12)-Si(9) bond length is 2.84 Å. There are ten inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(4), one Mg(8), one Mg(9), two equivalent Mg(5), one Si(5), and one Si(8) atom. The Si(1)-Si(5) bond length is 2.46 Å. The Si(1)-Si(8) bond length is 2.43 Å. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to one Mg(3), one Mg(4), one Mg(7), two equivalent Mg(2), two equivalent Mg(8), one Si(6), and one Si(7) atom. The Si(2)-Si(6) bond length is 2.45 Å. The Si(2)-Si(7) bond length is 2.56 Å. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(10), one Mg(11), one Mg(12), one Mg(6), two equivalent Mg(3), one Si(10), and one Si(6) atom. The Si(3)-Si(10) bond length is 2.37 Å. The Si(3)-Si(6) bond length is 2.41 Å. In the fourth Si site, Si(4) is bonded in a 8-coordinate geometry to one Mg(11), one Mg(12), one Mg(5), one Mg(9), two equivalent Mg(1), one Si(8), and one Si(9) atom. The Si(4)-Si(8) bond length is 2.44 Å. The Si(4)-Si(9) bond length is 2.37 Å. In the fifth Si site, Si(5) is bonded in a 9-coordinate geometry to one Mg(4), one Mg(5), one Mg(7), two equivalent Mg(2), two equivalent Mg(8), one Si(1), and one Si(8) atom. The Si(5)-Si(8) bond length is 2.56 Å. In the sixth Si site, Si(6) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(7), one Mg(8), two equivalent Mg(3), one Si(2), one Si(3), and one Si(7) atom. The Si(6)-Si(7) bond length is 2.50 Å. In the seventh Si site, Si(7) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(3), one Mg(6), two equivalent Mg(7), one Si(10), one Si(2), and one Si(6) atom. The Si(7)-Si(10) bond length is 2.48 Å. In the eighth Si site, Si(8) is bonded in a 8-coordinate geometry to one Mg(5), one Mg(8), one Mg(9), two equivalent Mg(4), one Si(1), one Si(4), and one Si(5) atom. In the ninth Si site, Si(9) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(10), one Mg(11), one Mg(12), one Mg(5), two equivalent Mg(9), and one Si(4) atom. In the tenth Si site, Si(10) is bonded in a 8-coordinate geometry to one Mg(11), one Mg(12), one Mg(3), one Mg(7), two equivalent Mg(6), one Si(3), and one Si(7) atom.