Li2Mg3Si2 crystallizes in the trigonal R3m space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 11-coordinate geometry to three equivalent Li(2), one Mg(2), one Mg(3), three equivalent Mg(1), and three equivalent Si(1) atoms. In the second Li site, Li(2) is bonded to three equivalent Li(1), one Si(2), and three equivalent Si(1) atoms to form distorted edge-sharing LiLi3Si4 tetrahedra. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 7-coordinate geometry to three equivalent Li(1), one Si(1), and three equivalent Si(2) atoms. In the second Mg site, Mg(2) is bonded in a 5-coordinate geometry to one Li(1), one Si(2), and three equivalent Si(1) atoms. In the third Mg site, Mg(3) is bonded in a 5-coordinate geometry to one Li(1), one Si(1), and three equivalent Si(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted body-centered cubic geometry to three equivalent Li(1), three equivalent Li(2), one Mg(1), one Mg(3), and three equivalent Mg(2) atoms. In the second Si site, Si(2) is bonded in a body-centered cubic geometry to one Li(2), one Mg(2), three equivalent Mg(1), and three equivalent Mg(3) atoms.
Li2Mg3Si2 crystallizes in the trigonal R3m space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 11-coordinate geometry to three equivalent Li(2), one Mg(2), one Mg(3), three equivalent Mg(1), and three equivalent Si(1) atoms. All Li(1)-Li(2) bond lengths are 2.75 Å. The Li(1)-Mg(2) bond length is 2.64 Å. The Li(1)-Mg(3) bond length is 3.01 Å. All Li(1)-Mg(1) bond lengths are 2.80 Å. All Li(1)-Si(1) bond lengths are 3.05 Å. In the second Li site, Li(2) is bonded to three equivalent Li(1), one Si(2), and three equivalent Si(1) atoms to form distorted edge-sharing LiLi3Si4 tetrahedra. The Li(2)-Si(2) bond length is 2.87 Å. All Li(2)-Si(1) bond lengths are 2.67 Å. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 7-coordinate geometry to three equivalent Li(1), one Si(1), and three equivalent Si(2) atoms. The Mg(1)-Si(1) bond length is 2.70 Å. All Mg(1)-Si(2) bond lengths are 2.72 Å. In the second Mg site, Mg(2) is bonded in a 5-coordinate geometry to one Li(1), one Si(2), and three equivalent Si(1) atoms. The Mg(2)-Si(2) bond length is 2.78 Å. All Mg(2)-Si(1) bond lengths are 2.78 Å. In the third Mg site, Mg(3) is bonded in a 5-coordinate geometry to one Li(1), one Si(1), and three equivalent Si(2) atoms. The Mg(3)-Si(1) bond length is 2.70 Å. All Mg(3)-Si(2) bond lengths are 2.81 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted body-centered cubic geometry to three equivalent Li(1), three equivalent Li(2), one Mg(1), one Mg(3), and three equivalent Mg(2) atoms. In the second Si site, Si(2) is bonded in a body-centered cubic geometry to one Li(2), one Mg(2), three equivalent Mg(1), and three equivalent Mg(3) atoms.