BiMnAsO5 crystallizes in the triclinic P-1 space group. Mn(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form MnO6 octahedra that share  a cornercorner with one Bi(1)O5 square pyramid, corners with four equivalent As(1)O4 tetrahedra,  an edgeedge with one Mn(1)O6 octahedra, and edges with three equivalent Bi(1)O5 square pyramids. Bi(1) is bonded to one O(2), one O(3), one O(5), and two equivalent O(1) atoms to form distorted BiO5 square pyramids that share  a cornercorner with one Mn(1)O6 octahedra, corners with three equivalent As(1)O4 tetrahedra, edges with three equivalent Mn(1)O6 octahedra, and  an edgeedge with one Bi(1)O5 square pyramid. The corner-sharing octahedral tilt angles are 43°. As(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form AsO4 tetrahedra that share corners with four equivalent Mn(1)O6 octahedra and corners with three equivalent Bi(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 50-56°. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mn(1) and two equivalent Bi(1) atoms to form edge-sharing OMn2Bi2 tetrahedra. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mn(1), one Bi(1), and one As(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Mn(1), one Bi(1), and one As(1) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Mn(1) and one As(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mn(1), one Bi(1), and one As(1) atom.
BiMnAsO5 crystallizes in the triclinic P-1 space group. Mn(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form MnO6 octahedra that share  a cornercorner with one Bi(1)O5 square pyramid, corners with four equivalent As(1)O4 tetrahedra,  an edgeedge with one Mn(1)O6 octahedra, and edges with three equivalent Bi(1)O5 square pyramids. The Mn(1)-O(2) bond length is 2.32 Å. The Mn(1)-O(3) bond length is 2.21 Å. The Mn(1)-O(4) bond length is 2.15 Å. The Mn(1)-O(5) bond length is 2.20 Å. There is one shorter (2.17 Å) and one longer (2.34 Å) Mn(1)-O(1) bond length. Bi(1) is bonded to one O(2), one O(3), one O(5), and two equivalent O(1) atoms to form distorted BiO5 square pyramids that share  a cornercorner with one Mn(1)O6 octahedra, corners with three equivalent As(1)O4 tetrahedra, edges with three equivalent Mn(1)O6 octahedra, and  an edgeedge with one Bi(1)O5 square pyramid. The corner-sharing octahedral tilt angles are 43°. The Bi(1)-O(2) bond length is 2.43 Å. The Bi(1)-O(3) bond length is 2.37 Å. The Bi(1)-O(5) bond length is 2.37 Å. There is one shorter (2.14 Å) and one longer (2.29 Å) Bi(1)-O(1) bond length. As(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form AsO4 tetrahedra that share corners with four equivalent Mn(1)O6 octahedra and corners with three equivalent Bi(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 50-56°. The As(1)-O(2) bond length is 1.74 Å. The As(1)-O(3) bond length is 1.73 Å. The As(1)-O(4) bond length is 1.71 Å. The As(1)-O(5) bond length is 1.73 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mn(1) and two equivalent Bi(1) atoms to form edge-sharing OMn2Bi2 tetrahedra. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mn(1), one Bi(1), and one As(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Mn(1), one Bi(1), and one As(1) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Mn(1) and one As(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mn(1), one Bi(1), and one As(1) atom.