MgMn2(B4O7)2 crystallizes in the monoclinic Pm space group. Mg(1) is bonded in a 2-coordinate geometry to one Mn(2), one O(1), and one O(10) atom. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 7-coordinate geometry to one O(7), two equivalent O(1), two equivalent O(6), and two equivalent O(9) atoms. In the second Mn site, Mn(2) is bonded in a 8-coordinate geometry to one Mg(1), one O(4), two equivalent O(2), two equivalent O(5), and two equivalent O(8) atoms. There are six inequivalent B sites. In the first B site, B(1) is bonded to one O(2), one O(3), and two equivalent O(8) atoms to form corner-sharing BO4 tetrahedra. In the second B site, B(2) is bonded in a trigonal planar geometry to one O(1) and two equivalent O(9) atoms. In the third B site, B(3) is bonded to one O(10), one O(7), one O(8), and one O(9) atom to form corner-sharing BO4 tetrahedra. In the fourth B site, B(4) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form corner-sharing BO4 tetrahedra. In the fifth B site, B(5) is bonded in a trigonal planar geometry to one O(2) and two equivalent O(5) atoms. In the sixth B site, B(6) is bonded to one O(1), one O(10), and two equivalent O(6) atoms to form corner-sharing BO4 tetrahedra. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), two equivalent Mn(1), one B(2), and one B(6) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to two equivalent Mn(2), one B(1), and one B(5) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one B(1) and two equivalent B(4) atoms. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Mn(2) and two equivalent B(4) atoms. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Mn(2), one B(4), and one B(5) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Mn(1), one B(4), and one B(6) atom. In the seventh O site, O(7) is bonded in a distorted water-like geometry to one Mn(1) and two equivalent B(3) atoms. In the eighth O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Mn(2), one B(1), and one B(3) atom. In the ninth O site, O(9) is bonded in a distorted bent 120 degrees geometry to one Mn(1), one B(2), and one B(3) atom. In the tenth O site, O(10) is bonded in a distorted tetrahedral geometry to one Mg(1), one B(6), and two equivalent B(3) atoms.
MgMn2(B4O7)2 crystallizes in the monoclinic Pm space group. Mg(1) is bonded in a 2-coordinate geometry to one Mn(2), one O(1), and one O(10) atom. The Mg(1)-Mn(2) bond length is 2.92 Å. The Mg(1)-O(1) bond length is 2.12 Å. The Mg(1)-O(10) bond length is 2.46 Å. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 7-coordinate geometry to one O(7), two equivalent O(1), two equivalent O(6), and two equivalent O(9) atoms. The Mn(1)-O(7) bond length is 2.67 Å. Both Mn(1)-O(1) bond lengths are 2.68 Å. Both Mn(1)-O(6) bond lengths are 2.08 Å. Both Mn(1)-O(9) bond lengths are 2.25 Å. In the second Mn site, Mn(2) is bonded in a 8-coordinate geometry to one Mg(1), one O(4), two equivalent O(2), two equivalent O(5), and two equivalent O(8) atoms. The Mn(2)-O(4) bond length is 2.43 Å. Both Mn(2)-O(2) bond lengths are 2.59 Å. Both Mn(2)-O(5) bond lengths are 2.43 Å. Both Mn(2)-O(8) bond lengths are 2.26 Å. There are six inequivalent B sites. In the first B site, B(1) is bonded to one O(2), one O(3), and two equivalent O(8) atoms to form corner-sharing BO4 tetrahedra. The B(1)-O(2) bond length is 1.48 Å. The B(1)-O(3) bond length is 1.55 Å. Both B(1)-O(8) bond lengths are 1.45 Å. In the second B site, B(2) is bonded in a trigonal planar geometry to one O(1) and two equivalent O(9) atoms. The B(2)-O(1) bond length is 1.41 Å. Both B(2)-O(9) bond lengths are 1.36 Å. In the third B site, B(3) is bonded to one O(10), one O(7), one O(8), and one O(9) atom to form corner-sharing BO4 tetrahedra. The B(3)-O(10) bond length is 1.61 Å. The B(3)-O(7) bond length is 1.46 Å. The B(3)-O(8) bond length is 1.44 Å. The B(3)-O(9) bond length is 1.52 Å. In the fourth B site, B(4) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form corner-sharing BO4 tetrahedra. The B(4)-O(3) bond length is 1.57 Å. The B(4)-O(4) bond length is 1.47 Å. The B(4)-O(5) bond length is 1.47 Å. The B(4)-O(6) bond length is 1.51 Å. In the fifth B site, B(5) is bonded in a trigonal planar geometry to one O(2) and two equivalent O(5) atoms. The B(5)-O(2) bond length is 1.39 Å. Both B(5)-O(5) bond lengths are 1.36 Å. In the sixth B site, B(6) is bonded to one O(1), one O(10), and two equivalent O(6) atoms to form corner-sharing BO4 tetrahedra. The B(6)-O(1) bond length is 1.55 Å. The B(6)-O(10) bond length is 1.57 Å. Both B(6)-O(6) bond lengths are 1.42 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), two equivalent Mn(1), one B(2), and one B(6) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to two equivalent Mn(2), one B(1), and one B(5) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one B(1) and two equivalent B(4) atoms. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Mn(2) and two equivalent B(4) atoms. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Mn(2), one B(4), and one B(5) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Mn(1), one B(4), and one B(6) atom. In the seventh O site, O(7) is bonded in a distorted water-like geometry to one Mn(1) and two equivalent B(3) atoms. In the eighth O site, O(8) is bonded in a distorted bent 120 degrees geometry to one Mn(2), one B(1), and one B(3) atom. In the ninth O site, O(9) is bonded in a distorted bent 120 degrees geometry to one Mn(1), one B(2), and one B(3) atom. In the tenth O site, O(10) is bonded in a distorted tetrahedral geometry to one Mg(1), one B(6), and two equivalent B(3) atoms.