MgSi2 crystallizes in the monoclinic P2_1/m space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 14-coordinate geometry to two equivalent Mg(3), two equivalent Si(2), two equivalent Si(4), four equivalent Si(1), and four equivalent Si(3) atoms. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to two equivalent Si(1), two equivalent Si(2), two equivalent Si(3), and four equivalent Si(4) atoms. In the third Mg site, Mg(3) is bonded in a 10-coordinate geometry to two equivalent Mg(1), two equivalent Si(2), two equivalent Si(3), two equivalent Si(4), and four equivalent Si(1) atoms. In the fourth Mg site, Mg(4) is bonded in a 6-coordinate geometry to two equivalent Si(1), two equivalent Si(2), two equivalent Si(3), and four equivalent Si(4) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 10-coordinate geometry to one Mg(2), one Mg(4), two equivalent Mg(1), two equivalent Mg(3), one Si(2), one Si(3), and two equivalent Si(1) atoms. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(2), one Mg(3), one Mg(4), one Si(1), one Si(4), and two equivalent Si(2) atoms. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to one Mg(2), one Mg(3), one Mg(4), two equivalent Mg(1), one Si(1), one Si(4), and two equivalent Si(3) atoms. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to one Mg(1), one Mg(3), two equivalent Mg(2), two equivalent Mg(4), one Si(2), one Si(3), and one Si(4) atom.
MgSi2 crystallizes in the monoclinic P2_1/m space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 14-coordinate geometry to two equivalent Mg(3), two equivalent Si(2), two equivalent Si(4), four equivalent Si(1), and four equivalent Si(3) atoms. Both Mg(1)-Mg(3) bond lengths are 3.05 Å. Both Mg(1)-Si(2) bond lengths are 2.99 Å. Both Mg(1)-Si(4) bond lengths are 3.07 Å. There are two shorter (2.99 Å) and two longer (3.08 Å) Mg(1)-Si(1) bond lengths. There are two shorter (2.84 Å) and two longer (2.93 Å) Mg(1)-Si(3) bond lengths. In the second Mg site, Mg(2) is bonded in a 10-coordinate geometry to two equivalent Si(1), two equivalent Si(2), two equivalent Si(3), and four equivalent Si(4) atoms. Both Mg(2)-Si(1) bond lengths are 2.98 Å. Both Mg(2)-Si(2) bond lengths are 3.04 Å. Both Mg(2)-Si(3) bond lengths are 2.95 Å. There are two shorter (2.79 Å) and two longer (2.90 Å) Mg(2)-Si(4) bond lengths. In the third Mg site, Mg(3) is bonded in a 10-coordinate geometry to two equivalent Mg(1), two equivalent Si(2), two equivalent Si(3), two equivalent Si(4), and four equivalent Si(1) atoms. Both Mg(3)-Si(2) bond lengths are 2.90 Å. Both Mg(3)-Si(3) bond lengths are 3.01 Å. Both Mg(3)-Si(4) bond lengths are 2.84 Å. There are two shorter (2.82 Å) and two longer (2.84 Å) Mg(3)-Si(1) bond lengths. In the fourth Mg site, Mg(4) is bonded in a 6-coordinate geometry to two equivalent Si(1), two equivalent Si(2), two equivalent Si(3), and four equivalent Si(4) atoms. Both Mg(4)-Si(1) bond lengths are 3.23 Å. Both Mg(4)-Si(2) bond lengths are 2.80 Å. Both Mg(4)-Si(3) bond lengths are 3.17 Å. There are two shorter (2.90 Å) and two longer (3.05 Å) Mg(4)-Si(4) bond lengths. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 10-coordinate geometry to one Mg(2), one Mg(4), two equivalent Mg(1), two equivalent Mg(3), one Si(2), one Si(3), and two equivalent Si(1) atoms. The Si(1)-Si(2) bond length is 2.70 Å. The Si(1)-Si(3) bond length is 2.47 Å. There is one shorter (2.46 Å) and one longer (2.77 Å) Si(1)-Si(1) bond length. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Mg(1), one Mg(2), one Mg(3), one Mg(4), one Si(1), one Si(4), and two equivalent Si(2) atoms. The Si(2)-Si(4) bond length is 2.48 Å. There is one shorter (2.40 Å) and one longer (2.53 Å) Si(2)-Si(2) bond length. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to one Mg(2), one Mg(3), one Mg(4), two equivalent Mg(1), one Si(1), one Si(4), and two equivalent Si(3) atoms. The Si(3)-Si(4) bond length is 2.59 Å. There is one shorter (2.44 Å) and one longer (2.62 Å) Si(3)-Si(3) bond length. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to one Mg(1), one Mg(3), two equivalent Mg(2), two equivalent Mg(4), one Si(2), one Si(3), and one Si(4) atom. The Si(4)-Si(4) bond length is 2.43 Å.