Mn2Si4N7 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one N(2), one N(4), two equivalent N(1), and two equivalent N(3) atoms to form MnN6 octahedra that share corners with three equivalent Si(1)N4 tetrahedra, corners with three equivalent Si(3)N4 tetrahedra, and corners with six equivalent Si(2)N4 tetrahedra. In the second Mn site, Mn(2) is bonded in a 6-coordinate geometry to two equivalent N(1), two equivalent N(2), and two equivalent N(3) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one N(4), one N(5), and two equivalent N(3) atoms to form SiN4 tetrahedra that share corners with three equivalent Mn(1)N6 octahedra, corners with two equivalent Si(3)N4 tetrahedra, and corners with four equivalent Si(2)N4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-63°. In the second Si site, Si(2) is bonded to one N(1), one N(2), one N(3), and one N(5) atom to form SiN4 tetrahedra that share corners with three equivalent Mn(1)N6 octahedra, corners with two equivalent Si(1)N4 tetrahedra, corners with two equivalent Si(2)N4 tetrahedra, and corners with two equivalent Si(3)N4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-60°. In the third Si site, Si(3) is bonded to one N(4), one N(5), and two equivalent N(1) atoms to form SiN4 tetrahedra that share corners with three equivalent Mn(1)N6 octahedra, corners with two equivalent Si(1)N4 tetrahedra, and corners with four equivalent Si(2)N4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-57°. There are five inequivalent N sites. In the first N site, N(5) is bonded to one Si(1), one Si(3), and two equivalent Si(2) atoms to form corner-sharing NSi4 tetrahedra. In the second N site, N(1) is bonded to one Mn(1), one Mn(2), one Si(2), and one Si(3) atom to form distorted NMn2Si2 trigonal pyramids that share corners with two equivalent N(5)Si4 tetrahedra,  a cornercorner with one N(1)Mn2Si2 trigonal pyramid, corners with five equivalent N(3)Mn2Si2 trigonal pyramids, and  an edgeedge with one N(1)Mn2Si2 trigonal pyramid. In the third N site, N(2) is bonded in a 5-coordinate geometry to one Mn(1), two equivalent Mn(2), and two equivalent Si(2) atoms. In the fourth N site, N(3) is bonded to one Mn(1), one Mn(2), one Si(1), and one Si(2) atom to form distorted NMn2Si2 trigonal pyramids that share corners with two equivalent N(5)Si4 tetrahedra,  a cornercorner with one N(3)Mn2Si2 trigonal pyramid, corners with five equivalent N(1)Mn2Si2 trigonal pyramids, and  an edgeedge with one N(3)Mn2Si2 trigonal pyramid. In the fifth N site, N(4) is bonded in a trigonal planar geometry to one Mn(1), one Si(1), and one Si(3) atom.
Mn2Si4N7 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one N(2), one N(4), two equivalent N(1), and two equivalent N(3) atoms to form MnN6 octahedra that share corners with three equivalent Si(1)N4 tetrahedra, corners with three equivalent Si(3)N4 tetrahedra, and corners with six equivalent Si(2)N4 tetrahedra. The Mn(1)-N(2) bond length is 2.04 Å. The Mn(1)-N(4) bond length is 1.95 Å. Both Mn(1)-N(1) bond lengths are 2.14 Å. Both Mn(1)-N(3) bond lengths are 2.28 Å. In the second Mn site, Mn(2) is bonded in a 6-coordinate geometry to two equivalent N(1), two equivalent N(2), and two equivalent N(3) atoms. Both Mn(2)-N(1) bond lengths are 2.47 Å. There is one shorter (2.42 Å) and one longer (2.80 Å) Mn(2)-N(2) bond length. Both Mn(2)-N(3) bond lengths are 2.28 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one N(4), one N(5), and two equivalent N(3) atoms to form SiN4 tetrahedra that share corners with three equivalent Mn(1)N6 octahedra, corners with two equivalent Si(3)N4 tetrahedra, and corners with four equivalent Si(2)N4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-63°. The Si(1)-N(4) bond length is 1.75 Å. The Si(1)-N(5) bond length is 1.84 Å. Both Si(1)-N(3) bond lengths are 1.72 Å. In the second Si site, Si(2) is bonded to one N(1), one N(2), one N(3), and one N(5) atom to form SiN4 tetrahedra that share corners with three equivalent Mn(1)N6 octahedra, corners with two equivalent Si(1)N4 tetrahedra, corners with two equivalent Si(2)N4 tetrahedra, and corners with two equivalent Si(3)N4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-60°. The Si(2)-N(1) bond length is 1.72 Å. The Si(2)-N(2) bond length is 1.76 Å. The Si(2)-N(3) bond length is 1.72 Å. The Si(2)-N(5) bond length is 1.87 Å. In the third Si site, Si(3) is bonded to one N(4), one N(5), and two equivalent N(1) atoms to form SiN4 tetrahedra that share corners with three equivalent Mn(1)N6 octahedra, corners with two equivalent Si(1)N4 tetrahedra, and corners with four equivalent Si(2)N4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-57°. The Si(3)-N(4) bond length is 1.73 Å. The Si(3)-N(5) bond length is 1.87 Å. Both Si(3)-N(1) bond lengths are 1.74 Å. There are five inequivalent N sites. In the first N site, N(5) is bonded to one Si(1), one Si(3), and two equivalent Si(2) atoms to form corner-sharing NSi4 tetrahedra. In the second N site, N(1) is bonded to one Mn(1), one Mn(2), one Si(2), and one Si(3) atom to form distorted NMn2Si2 trigonal pyramids that share corners with two equivalent N(5)Si4 tetrahedra,  a cornercorner with one N(1)Mn2Si2 trigonal pyramid, corners with five equivalent N(3)Mn2Si2 trigonal pyramids, and  an edgeedge with one N(1)Mn2Si2 trigonal pyramid. In the third N site, N(2) is bonded in a 5-coordinate geometry to one Mn(1), two equivalent Mn(2), and two equivalent Si(2) atoms. In the fourth N site, N(3) is bonded to one Mn(1), one Mn(2), one Si(1), and one Si(2) atom to form distorted NMn2Si2 trigonal pyramids that share corners with two equivalent N(5)Si4 tetrahedra,  a cornercorner with one N(3)Mn2Si2 trigonal pyramid, corners with five equivalent N(1)Mn2Si2 trigonal pyramids, and  an edgeedge with one N(3)Mn2Si2 trigonal pyramid. In the fifth N site, N(4) is bonded in a trigonal planar geometry to one Mn(1), one Si(1), and one Si(3) atom.