MgSi2 is Magnesium tetraboride-like structured and crystallizes in the monoclinic Cm space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 9-coordinate geometry to one Si(3), two equivalent Si(1), three equivalent Si(2), and three equivalent Si(5) atoms. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to one Si(2), one Si(4), two equivalent Si(7), three equivalent Si(1), and three equivalent Si(6) atoms. In the third Mg site, Mg(3) is bonded in a 9-coordinate geometry to one Si(3), two equivalent Si(4), two equivalent Si(6), two equivalent Si(7), and two equivalent Si(8) atoms. In the fourth Mg site, Mg(4) is bonded in a 6-coordinate geometry to one Si(4), one Si(5), two equivalent Si(8), and three equivalent Si(3) atoms. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to two equivalent Mg(1), three equivalent Mg(2), one Si(2), and two equivalent Si(6) atoms. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Mg(2), three equivalent Mg(1), one Si(1), and two equivalent Si(5) atoms. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(3), three equivalent Mg(4), one Si(5), and two equivalent Si(8) atoms. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(2), one Mg(4), two equivalent Mg(3), one Si(6), and two equivalent Si(7) atoms. In the fifth Si site, Si(5) is bonded in a 7-coordinate geometry to one Mg(4), three equivalent Mg(1), one Si(3), and two equivalent Si(2) atoms. In the sixth Si site, Si(6) is bonded in a 9-coordinate geometry to two equivalent Mg(3), three equivalent Mg(2), one Si(4), one Si(7), and two equivalent Si(1) atoms. In the seventh Si site, Si(7) is bonded in a 8-coordinate geometry to two equivalent Mg(2), two equivalent Mg(3), one Si(6), one Si(8), and two equivalent Si(4) atoms. In the eighth Si site, Si(8) is bonded in a 7-coordinate geometry to two equivalent Mg(3), two equivalent Mg(4), one Si(7), and two equivalent Si(3) atoms.
MgSi2 is Magnesium tetraboride-like structured and crystallizes in the monoclinic Cm space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 9-coordinate geometry to one Si(3), two equivalent Si(1), three equivalent Si(2), and three equivalent Si(5) atoms. The Mg(1)-Si(3) bond length is 2.92 Å. Both Mg(1)-Si(1) bond lengths are 3.14 Å. There is one shorter (2.93 Å) and two longer (3.07 Å) Mg(1)-Si(2) bond lengths. There is one shorter (3.00 Å) and two longer (3.01 Å) Mg(1)-Si(5) bond lengths. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to one Si(2), one Si(4), two equivalent Si(7), three equivalent Si(1), and three equivalent Si(6) atoms. The Mg(2)-Si(2) bond length is 2.67 Å. The Mg(2)-Si(4) bond length is 2.89 Å. Both Mg(2)-Si(7) bond lengths are 2.98 Å. There are two shorter (2.94 Å) and one longer (3.05 Å) Mg(2)-Si(1) bond length. All Mg(2)-Si(6) bond lengths are 3.06 Å. In the third Mg site, Mg(3) is bonded in a 9-coordinate geometry to one Si(3), two equivalent Si(4), two equivalent Si(6), two equivalent Si(7), and two equivalent Si(8) atoms. The Mg(3)-Si(3) bond length is 2.75 Å. Both Mg(3)-Si(4) bond lengths are 2.73 Å. Both Mg(3)-Si(6) bond lengths are 3.04 Å. Both Mg(3)-Si(7) bond lengths are 2.83 Å. Both Mg(3)-Si(8) bond lengths are 2.98 Å. In the fourth Mg site, Mg(4) is bonded in a 6-coordinate geometry to one Si(4), one Si(5), two equivalent Si(8), and three equivalent Si(3) atoms. The Mg(4)-Si(4) bond length is 2.94 Å. The Mg(4)-Si(5) bond length is 2.81 Å. Both Mg(4)-Si(8) bond lengths are 2.90 Å. There are two shorter (2.85 Å) and one longer (3.12 Å) Mg(4)-Si(3) bond length. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to two equivalent Mg(1), three equivalent Mg(2), one Si(2), and two equivalent Si(6) atoms. The Si(1)-Si(2) bond length is 2.40 Å. Both Si(1)-Si(6) bond lengths are 2.46 Å. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Mg(2), three equivalent Mg(1), one Si(1), and two equivalent Si(5) atoms. Both Si(2)-Si(5) bond lengths are 2.36 Å. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(3), three equivalent Mg(4), one Si(5), and two equivalent Si(8) atoms. The Si(3)-Si(5) bond length is 2.42 Å. Both Si(3)-Si(8) bond lengths are 2.43 Å. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(2), one Mg(4), two equivalent Mg(3), one Si(6), and two equivalent Si(7) atoms. The Si(4)-Si(6) bond length is 2.41 Å. Both Si(4)-Si(7) bond lengths are 2.41 Å. In the fifth Si site, Si(5) is bonded in a 7-coordinate geometry to one Mg(4), three equivalent Mg(1), one Si(3), and two equivalent Si(2) atoms. In the sixth Si site, Si(6) is bonded in a 9-coordinate geometry to two equivalent Mg(3), three equivalent Mg(2), one Si(4), one Si(7), and two equivalent Si(1) atoms. The Si(6)-Si(7) bond length is 2.53 Å. In the seventh Si site, Si(7) is bonded in a 8-coordinate geometry to two equivalent Mg(2), two equivalent Mg(3), one Si(6), one Si(8), and two equivalent Si(4) atoms. The Si(7)-Si(8) bond length is 2.48 Å. In the eighth Si site, Si(8) is bonded in a 7-coordinate geometry to two equivalent Mg(3), two equivalent Mg(4), one Si(7), and two equivalent Si(3) atoms.