YCu3Mn4O12 crystallizes in the monoclinic Cm space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to one O(14), one O(2), one O(3), one O(5), two equivalent O(10), two equivalent O(11), two equivalent O(15), and two equivalent O(8) atoms to form YO12 cuboctahedra that share faces with two equivalent Mn(3)O6 octahedra, faces with two equivalent Mn(4)O6 octahedra, and faces with four equivalent Mn(2)O6 octahedra. In the second Y site, Y(2) is bonded to one O(1), one O(13), one O(4), one O(6), two equivalent O(12), two equivalent O(16), two equivalent O(7), and two equivalent O(9) atoms to form YO12 cuboctahedra that share faces with two equivalent Mn(3)O6 octahedra, faces with two equivalent Mn(4)O6 octahedra, and faces with four equivalent Mn(1)O6 octahedra. There are four inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(12), one O(16), one O(4), one O(7), and one O(9) atom to form MnO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with two equivalent Mn(3)O6 octahedra, corners with two equivalent Mn(4)O6 octahedra, and faces with two equivalent Y(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 39-42°. In the second Mn site, Mn(2) is bonded to one O(10), one O(11), one O(15), one O(2), one O(3), and one O(8) atom to form MnO6 octahedra that share corners with two equivalent Mn(2)O6 octahedra, corners with two equivalent Mn(3)O6 octahedra, corners with two equivalent Mn(4)O6 octahedra, and faces with two equivalent Y(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 40-43°. In the third Mn site, Mn(3) is bonded to one O(11), one O(13), one O(15), one O(5), one O(7), and one O(9) atom to form MnO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with two equivalent Mn(2)O6 octahedra, corners with two equivalent Mn(3)O6 octahedra,  a faceface with one Y(1)O12 cuboctahedra, and  a faceface with one Y(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 39-43°. In the fourth Mn site, Mn(4) is bonded to one O(10), one O(12), one O(14), one O(16), one O(6), and one O(8) atom to form MnO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with two equivalent Mn(2)O6 octahedra, corners with two equivalent Mn(4)O6 octahedra,  a faceface with one Y(1)O12 cuboctahedra, and  a faceface with one Y(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 41-42°. There are six inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a square co-planar geometry to two equivalent O(16) and two equivalent O(7) atoms. In the second Cu site, Cu(2) is bonded in a square co-planar geometry to one O(1), one O(13), one O(3), and one O(5) atom. In the third Cu site, Cu(3) is bonded in a square co-planar geometry to one O(14), one O(2), one O(4), and one O(6) atom. In the fourth Cu site, Cu(4) is bonded in a square co-planar geometry to two equivalent O(11) and two equivalent O(9) atoms. In the fifth Cu site, Cu(5) is bonded in a square co-planar geometry to two equivalent O(10) and two equivalent O(12) atoms. In the sixth Cu site, Cu(6) is bonded in a square co-planar geometry to two equivalent O(15) and two equivalent O(8) atoms. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Y(2), two equivalent Mn(1), and one Cu(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Y(1), two equivalent Mn(2), and one Cu(3) atom. In the third O site, O(3) is bonded to one Y(1), two equivalent Mn(2), and one Cu(2) atom to form a mixture of distorted edge and corner-sharing OYMn2Cu tetrahedra. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Y(2), two equivalent Mn(1), and one Cu(3) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Y(1), two equivalent Mn(3), and one Cu(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Y(2), two equivalent Mn(4), and one Cu(3) atom. In the seventh O site, O(7) is bonded to one Y(2), one Mn(1), one Mn(3), and one Cu(1) atom to form a mixture of distorted edge and corner-sharing OYMn2Cu tetrahedra. In the eighth O site, O(8) is bonded to one Y(1), one Mn(2), one Mn(4), and one Cu(6) atom to form a mixture of distorted edge and corner-sharing OYMn2Cu tetrahedra. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Y(2), one Mn(1), one Mn(3), and one Cu(4) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one Y(1), one Mn(2), one Mn(4), and one Cu(5) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one Y(1), one Mn(2), one Mn(3), and one Cu(4) atom. In the twelfth O site, O(12) is bonded in a 4-coordinate geometry to one Y(2), one Mn(1), one Mn(4), and one Cu(5) atom. In the thirteenth O site, O(13) is bonded in a 4-coordinate geometry to one Y(2), two equivalent Mn(3), and one Cu(2) atom. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one Y(1), two equivalent Mn(4), and one Cu(3) atom. In the fifteenth O site, O(15) is bonded to one Y(1), one Mn(2), one Mn(3), and one Cu(6) atom to form a mixture of distorted edge and corner-sharing OYMn2Cu tetrahedra. In the sixteenth O site, O(16) is bonded to one Y(2), one Mn(1), one Mn(4), and one Cu(1) atom to form a mixture of distorted edge and corner-sharing OYMn2Cu tetrahedra.
YCu3Mn4O12 crystallizes in the monoclinic Cm space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded to one O(14), one O(2), one O(3), one O(5), two equivalent O(10), two equivalent O(11), two equivalent O(15), and two equivalent O(8) atoms to form YO12 cuboctahedra that share faces with two equivalent Mn(3)O6 octahedra, faces with two equivalent Mn(4)O6 octahedra, and faces with four equivalent Mn(2)O6 octahedra. The Y(1)-O(14) bond length is 2.60 Å. The Y(1)-O(2) bond length is 2.60 Å. The Y(1)-O(3) bond length is 2.54 Å. The Y(1)-O(5) bond length is 2.54 Å. Both Y(1)-O(10) bond lengths are 2.58 Å. Both Y(1)-O(11) bond lengths are 2.58 Å. Both Y(1)-O(15) bond lengths are 2.55 Å. Both Y(1)-O(8) bond lengths are 2.57 Å. In the second Y site, Y(2) is bonded to one O(1), one O(13), one O(4), one O(6), two equivalent O(12), two equivalent O(16), two equivalent O(7), and two equivalent O(9) atoms to form YO12 cuboctahedra that share faces with two equivalent Mn(3)O6 octahedra, faces with two equivalent Mn(4)O6 octahedra, and faces with four equivalent Mn(1)O6 octahedra. The Y(2)-O(1) bond length is 2.57 Å. The Y(2)-O(13) bond length is 2.55 Å. The Y(2)-O(4) bond length is 2.64 Å. The Y(2)-O(6) bond length is 2.62 Å. Both Y(2)-O(12) bond lengths are 2.57 Å. Both Y(2)-O(16) bond lengths are 2.53 Å. Both Y(2)-O(7) bond lengths are 2.52 Å. Both Y(2)-O(9) bond lengths are 2.57 Å. There are four inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(12), one O(16), one O(4), one O(7), and one O(9) atom to form MnO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with two equivalent Mn(3)O6 octahedra, corners with two equivalent Mn(4)O6 octahedra, and faces with two equivalent Y(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 39-42°. The Mn(1)-O(1) bond length is 1.95 Å. The Mn(1)-O(12) bond length is 2.01 Å. The Mn(1)-O(16) bond length is 1.95 Å. The Mn(1)-O(4) bond length is 1.98 Å. The Mn(1)-O(7) bond length is 1.95 Å. The Mn(1)-O(9) bond length is 2.00 Å. In the second Mn site, Mn(2) is bonded to one O(10), one O(11), one O(15), one O(2), one O(3), and one O(8) atom to form MnO6 octahedra that share corners with two equivalent Mn(2)O6 octahedra, corners with two equivalent Mn(3)O6 octahedra, corners with two equivalent Mn(4)O6 octahedra, and faces with two equivalent Y(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 40-43°. The Mn(2)-O(10) bond length is 2.00 Å. The Mn(2)-O(11) bond length is 1.99 Å. The Mn(2)-O(15) bond length is 2.00 Å. The Mn(2)-O(2) bond length is 1.98 Å. The Mn(2)-O(3) bond length is 1.96 Å. The Mn(2)-O(8) bond length is 2.00 Å. In the third Mn site, Mn(3) is bonded to one O(11), one O(13), one O(15), one O(5), one O(7), and one O(9) atom to form MnO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with two equivalent Mn(2)O6 octahedra, corners with two equivalent Mn(3)O6 octahedra,  a faceface with one Y(1)O12 cuboctahedra, and  a faceface with one Y(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 39-43°. The Mn(3)-O(11) bond length is 2.01 Å. The Mn(3)-O(13) bond length is 1.96 Å. The Mn(3)-O(15) bond length is 1.97 Å. The Mn(3)-O(5) bond length is 1.97 Å. The Mn(3)-O(7) bond length is 1.95 Å. The Mn(3)-O(9) bond length is 2.02 Å. In the fourth Mn site, Mn(4) is bonded to one O(10), one O(12), one O(14), one O(16), one O(6), and one O(8) atom to form MnO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with two equivalent Mn(2)O6 octahedra, corners with two equivalent Mn(4)O6 octahedra,  a faceface with one Y(1)O12 cuboctahedra, and  a faceface with one Y(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 41-42°. The Mn(4)-O(10) bond length is 1.99 Å. The Mn(4)-O(12) bond length is 2.00 Å. The Mn(4)-O(14) bond length is 1.98 Å. The Mn(4)-O(16) bond length is 1.96 Å. The Mn(4)-O(6) bond length is 1.97 Å. The Mn(4)-O(8) bond length is 1.97 Å. There are six inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a square co-planar geometry to two equivalent O(16) and two equivalent O(7) atoms. Both Cu(1)-O(16) bond lengths are 1.98 Å. Both Cu(1)-O(7) bond lengths are 1.98 Å. In the second Cu site, Cu(2) is bonded in a square co-planar geometry to one O(1), one O(13), one O(3), and one O(5) atom. The Cu(2)-O(1) bond length is 1.98 Å. The Cu(2)-O(13) bond length is 1.99 Å. The Cu(2)-O(3) bond length is 1.98 Å. The Cu(2)-O(5) bond length is 1.99 Å. In the third Cu site, Cu(3) is bonded in a square co-planar geometry to one O(14), one O(2), one O(4), and one O(6) atom. The Cu(3)-O(14) bond length is 1.94 Å. The Cu(3)-O(2) bond length is 1.93 Å. The Cu(3)-O(4) bond length is 1.94 Å. The Cu(3)-O(6) bond length is 1.94 Å. In the fourth Cu site, Cu(4) is bonded in a square co-planar geometry to two equivalent O(11) and two equivalent O(9) atoms. Both Cu(4)-O(11) bond lengths are 1.91 Å. Both Cu(4)-O(9) bond lengths are 1.91 Å. In the fifth Cu site, Cu(5) is bonded in a square co-planar geometry to two equivalent O(10) and two equivalent O(12) atoms. Both Cu(5)-O(10) bond lengths are 1.91 Å. Both Cu(5)-O(12) bond lengths are 1.91 Å. In the sixth Cu site, Cu(6) is bonded in a square co-planar geometry to two equivalent O(15) and two equivalent O(8) atoms. Both Cu(6)-O(15) bond lengths are 1.93 Å. Both Cu(6)-O(8) bond lengths are 1.93 Å. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Y(2), two equivalent Mn(1), and one Cu(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Y(1), two equivalent Mn(2), and one Cu(3) atom. In the third O site, O(3) is bonded to one Y(1), two equivalent Mn(2), and one Cu(2) atom to form a mixture of distorted edge and corner-sharing OYMn2Cu tetrahedra. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Y(2), two equivalent Mn(1), and one Cu(3) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Y(1), two equivalent Mn(3), and one Cu(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Y(2), two equivalent Mn(4), and one Cu(3) atom. In the seventh O site, O(7) is bonded to one Y(2), one Mn(1), one Mn(3), and one Cu(1) atom to form a mixture of distorted edge and corner-sharing OYMn2Cu tetrahedra. In the eighth O site, O(8) is bonded to one Y(1), one Mn(2), one Mn(4), and one Cu(6) atom to form a mixture of distorted edge and corner-sharing OYMn2Cu tetrahedra. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Y(2), one Mn(1), one Mn(3), and one Cu(4) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one Y(1), one Mn(2), one Mn(4), and one Cu(5) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one Y(1), one Mn(2), one Mn(3), and one Cu(4) atom. In the twelfth O site, O(12) is bonded in a 4-coordinate geometry to one Y(2), one Mn(1), one Mn(4), and one Cu(5) atom. In the thirteenth O site, O(13) is bonded in a 4-coordinate geometry to one Y(2), two equivalent Mn(3), and one Cu(2) atom. In the fourteenth O site, O(14) is bonded in a 3-coordinate geometry to one Y(1), two equivalent Mn(4), and one Cu(3) atom. In the fifteenth O site, O(15) is bonded to one Y(1), one Mn(2), one Mn(3), and one Cu(6) atom to form a mixture of distorted edge and corner-sharing OYMn2Cu tetrahedra. In the sixteenth O site, O(16) is bonded to one Y(2), one Mn(1), one Mn(4), and one Cu(1) atom to form a mixture of distorted edge and corner-sharing OYMn2Cu tetrahedra.