Mg15Y is Magnesium-derived structured and crystallizes in the hexagonal P-6m2 space group. There are six inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to six equivalent Mg(3) and six Mg(4,4) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(1)Mg12 cuboctahedra; corners with twelve equivalent Mg(2)Y2Mg10 cuboctahedra; edges with six equivalent Mg(3)Mg12 cuboctahedra; edges with twelve Mg(4,4)YMg11 cuboctahedra; faces with two equivalent Y(1)Mg12 cuboctahedra; faces with six equivalent Mg(3)Mg12 cuboctahedra; faces with six equivalent Mg(5)Mg12 cuboctahedra; and faces with six Mg(4,4)YMg11 cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(5), four equivalent Mg(2), four equivalent Mg(4), and two equivalent Y(1) atoms to form MgY2Mg10 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra; corners with six equivalent Mg(2)Y2Mg10 cuboctahedra; corners with eight equivalent Mg(3)Mg12 cuboctahedra; edges with two equivalent Y(1)Mg12 cuboctahedra; edges with four equivalent Mg(5)Mg12 cuboctahedra; edges with four equivalent Mg(2)Y2Mg10 cuboctahedra; edges with eight equivalent Mg(4)YMg11 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with two equivalent Mg(5)Mg12 cuboctahedra; faces with two equivalent Y(1)Mg12 cuboctahedra; faces with four equivalent Mg(2)Y2Mg10 cuboctahedra; and faces with ten Mg(4,4)YMg11 cuboctahedra. In the third Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(5), four equivalent Mg(3), and four equivalent Mg(4) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Y(1)Mg12 cuboctahedra; corners with six equivalent Mg(3)Mg12 cuboctahedra; corners with eight equivalent Mg(2)Y2Mg10 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with four equivalent Mg(3)Mg12 cuboctahedra; edges with four equivalent Mg(5)Mg12 cuboctahedra; edges with eight equivalent Mg(4)YMg11 cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Mg(5)Mg12 cuboctahedra; faces with two equivalent Mg(2)Y2Mg10 cuboctahedra; faces with four equivalent Mg(3)Mg12 cuboctahedra; and faces with ten Mg(4,4)YMg11 cuboctahedra. In the fourth Mg site, Mg(4) is bonded to one Mg(1); two equivalent Mg(2); two equivalent Mg(3); two equivalent Mg(5); four Mg(4,4); and one Y(1) atom to form MgYMg11 cuboctahedra that share corners with four equivalent Mg(5)Mg12 cuboctahedra; corners with fourteen Mg(4,4)YMg11 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(5)Mg12 cuboctahedra; edges with two equivalent Y(1)Mg12 cuboctahedra; edges with four equivalent Mg(3)Mg12 cuboctahedra; edges with four equivalent Mg(2)Y2Mg10 cuboctahedra; edges with four Mg(4,4)YMg11 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra;  a faceface with one Y(1)Mg12 cuboctahedra; faces with two equivalent Mg(5)Mg12 cuboctahedra; faces with five equivalent Mg(3)Mg12 cuboctahedra; faces with five equivalent Mg(2)Y2Mg10 cuboctahedra; and faces with six Mg(4,4)YMg11 cuboctahedra. In the fifth Mg site, Mg(4) is bonded to one Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(5), four equivalent Mg(4), and one Y(1) atom to form MgYMg11 cuboctahedra that share corners with four equivalent Mg(5)Mg12 cuboctahedra; corners with fourteen Mg(4,4)YMg11 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(5)Mg12 cuboctahedra; edges with two equivalent Y(1)Mg12 cuboctahedra; edges with four equivalent Mg(3)Mg12 cuboctahedra; edges with four equivalent Mg(2)Y2Mg10 cuboctahedra; edges with four equivalent Mg(4)YMg11 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra;  a faceface with one Y(1)Mg12 cuboctahedra; faces with two equivalent Mg(5)Mg12 cuboctahedra; faces with five equivalent Mg(3)Mg12 cuboctahedra; faces with five equivalent Mg(2)Y2Mg10 cuboctahedra; and faces with six Mg(4,4)YMg11 cuboctahedra. In the sixth Mg site, Mg(5) is bonded to three equivalent Mg(2); three equivalent Mg(3); and six Mg(4,4) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(5)Mg12 cuboctahedra; corners with twelve Mg(4,4)YMg11 cuboctahedra; edges with six equivalent Mg(3)Mg12 cuboctahedra; edges with six equivalent Mg(2)Y2Mg10 cuboctahedra; edges with six Mg(4,4)YMg11 cuboctahedra; faces with two equivalent Mg(5)Mg12 cuboctahedra; faces with three equivalent Mg(1)Mg12 cuboctahedra; faces with three equivalent Mg(3)Mg12 cuboctahedra; faces with three equivalent Mg(2)Y2Mg10 cuboctahedra; faces with three equivalent Y(1)Mg12 cuboctahedra; and faces with six Mg(4,4)YMg11 cuboctahedra. Y(1) is bonded to six equivalent Mg(2) and six Mg(4,4) atoms to form YMg12 cuboctahedra that share corners with six equivalent Y(1)Mg12 cuboctahedra; corners with twelve equivalent Mg(3)Mg12 cuboctahedra; edges with six equivalent Mg(2)Y2Mg10 cuboctahedra; edges with twelve Mg(4,4)YMg11 cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with six equivalent Mg(5)Mg12 cuboctahedra; faces with six equivalent Mg(2)Y2Mg10 cuboctahedra; and faces with six Mg(4,4)YMg11 cuboctahedra.
Mg15Y is Magnesium-derived structured and crystallizes in the hexagonal P-6m2 space group. There are six inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to six equivalent Mg(3) and six Mg(4,4) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(1)Mg12 cuboctahedra; corners with twelve equivalent Mg(2)Y2Mg10 cuboctahedra; edges with six equivalent Mg(3)Mg12 cuboctahedra; edges with twelve Mg(4,4)YMg11 cuboctahedra; faces with two equivalent Y(1)Mg12 cuboctahedra; faces with six equivalent Mg(3)Mg12 cuboctahedra; faces with six equivalent Mg(5)Mg12 cuboctahedra; and faces with six Mg(4,4)YMg11 cuboctahedra. All Mg(1)-Mg(3) bond lengths are 3.24 Å. All Mg(1)-Mg(4,4) bond lengths are 3.14 Å. In the second Mg site, Mg(2) is bonded to two equivalent Mg(5), four equivalent Mg(2), four equivalent Mg(4), and two equivalent Y(1) atoms to form MgY2Mg10 cuboctahedra that share corners with four equivalent Mg(1)Mg12 cuboctahedra; corners with six equivalent Mg(2)Y2Mg10 cuboctahedra; corners with eight equivalent Mg(3)Mg12 cuboctahedra; edges with two equivalent Y(1)Mg12 cuboctahedra; edges with four equivalent Mg(5)Mg12 cuboctahedra; edges with four equivalent Mg(2)Y2Mg10 cuboctahedra; edges with eight equivalent Mg(4)YMg11 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with two equivalent Mg(5)Mg12 cuboctahedra; faces with two equivalent Y(1)Mg12 cuboctahedra; faces with four equivalent Mg(2)Y2Mg10 cuboctahedra; and faces with ten Mg(4,4)YMg11 cuboctahedra. Both Mg(2)-Mg(5) bond lengths are 3.16 Å. There are two shorter (3.14 Å) and two longer (3.34 Å) Mg(2)-Mg(2) bond lengths. All Mg(2)-Mg(4) bond lengths are 3.20 Å. Both Mg(2)-Y(1) bond lengths are 3.24 Å. In the third Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(5), four equivalent Mg(3), and four equivalent Mg(4) atoms to form MgMg12 cuboctahedra that share corners with four equivalent Y(1)Mg12 cuboctahedra; corners with six equivalent Mg(3)Mg12 cuboctahedra; corners with eight equivalent Mg(2)Y2Mg10 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with four equivalent Mg(3)Mg12 cuboctahedra; edges with four equivalent Mg(5)Mg12 cuboctahedra; edges with eight equivalent Mg(4)YMg11 cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with two equivalent Mg(5)Mg12 cuboctahedra; faces with two equivalent Mg(2)Y2Mg10 cuboctahedra; faces with four equivalent Mg(3)Mg12 cuboctahedra; and faces with ten Mg(4,4)YMg11 cuboctahedra. Both Mg(3)-Mg(5) bond lengths are 3.23 Å. There are two shorter (3.23 Å) and two longer (3.25 Å) Mg(3)-Mg(3) bond lengths. All Mg(3)-Mg(4) bond lengths are 3.14 Å. In the fourth Mg site, Mg(4) is bonded to one Mg(1); two equivalent Mg(2); two equivalent Mg(3); two equivalent Mg(5); four Mg(4,4); and one Y(1) atom to form MgYMg11 cuboctahedra that share corners with four equivalent Mg(5)Mg12 cuboctahedra; corners with fourteen Mg(4,4)YMg11 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(5)Mg12 cuboctahedra; edges with two equivalent Y(1)Mg12 cuboctahedra; edges with four equivalent Mg(3)Mg12 cuboctahedra; edges with four equivalent Mg(2)Y2Mg10 cuboctahedra; edges with four Mg(4,4)YMg11 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra;  a faceface with one Y(1)Mg12 cuboctahedra; faces with two equivalent Mg(5)Mg12 cuboctahedra; faces with five equivalent Mg(3)Mg12 cuboctahedra; faces with five equivalent Mg(2)Y2Mg10 cuboctahedra; and faces with six Mg(4,4)YMg11 cuboctahedra. Both Mg(4)-Mg(5) bond lengths are 3.24 Å. There are two shorter (3.23 Å) and two longer (3.25 Å) Mg(4)-Mg(4,4) bond lengths. The Mg(4)-Y(1) bond length is 3.22 Å. In the fifth Mg site, Mg(4) is bonded to one Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(5), four equivalent Mg(4), and one Y(1) atom to form MgYMg11 cuboctahedra that share corners with four equivalent Mg(5)Mg12 cuboctahedra; corners with fourteen Mg(4,4)YMg11 cuboctahedra; edges with two equivalent Mg(1)Mg12 cuboctahedra; edges with two equivalent Mg(5)Mg12 cuboctahedra; edges with two equivalent Y(1)Mg12 cuboctahedra; edges with four equivalent Mg(3)Mg12 cuboctahedra; edges with four equivalent Mg(2)Y2Mg10 cuboctahedra; edges with four equivalent Mg(4)YMg11 cuboctahedra;  a faceface with one Mg(1)Mg12 cuboctahedra;  a faceface with one Y(1)Mg12 cuboctahedra; faces with two equivalent Mg(5)Mg12 cuboctahedra; faces with five equivalent Mg(3)Mg12 cuboctahedra; faces with five equivalent Mg(2)Y2Mg10 cuboctahedra; and faces with six Mg(4,4)YMg11 cuboctahedra. Both Mg(4)-Mg(2) bond lengths are 3.20 Å. Both Mg(4)-Mg(3) bond lengths are 3.14 Å. Both Mg(4)-Mg(5) bond lengths are 3.24 Å. The Mg(4)-Y(1) bond length is 3.22 Å. In the sixth Mg site, Mg(5) is bonded to three equivalent Mg(2); three equivalent Mg(3); and six Mg(4,4) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(5)Mg12 cuboctahedra; corners with twelve Mg(4,4)YMg11 cuboctahedra; edges with six equivalent Mg(3)Mg12 cuboctahedra; edges with six equivalent Mg(2)Y2Mg10 cuboctahedra; edges with six Mg(4,4)YMg11 cuboctahedra; faces with two equivalent Mg(5)Mg12 cuboctahedra; faces with three equivalent Mg(1)Mg12 cuboctahedra; faces with three equivalent Mg(3)Mg12 cuboctahedra; faces with three equivalent Mg(2)Y2Mg10 cuboctahedra; faces with three equivalent Y(1)Mg12 cuboctahedra; and faces with six Mg(4,4)YMg11 cuboctahedra. Y(1) is bonded to six equivalent Mg(2) and six Mg(4,4) atoms to form YMg12 cuboctahedra that share corners with six equivalent Y(1)Mg12 cuboctahedra; corners with twelve equivalent Mg(3)Mg12 cuboctahedra; edges with six equivalent Mg(2)Y2Mg10 cuboctahedra; edges with twelve Mg(4,4)YMg11 cuboctahedra; faces with two equivalent Mg(1)Mg12 cuboctahedra; faces with six equivalent Mg(5)Mg12 cuboctahedra; faces with six equivalent Mg(2)Y2Mg10 cuboctahedra; and faces with six Mg(4,4)YMg11 cuboctahedra.