ErW2BiO9 crystallizes in the orthorhombic Pmmn space group. Er(1) is bonded in a 7-coordinate geometry to one O(1), two equivalent O(5), and four equivalent O(6) atoms. There are two inequivalent W sites. In the first W site, W(1) is bonded to one O(1), two equivalent O(4), and two equivalent O(6) atoms to form corner-sharing WO5 trigonal bipyramids. In the second W site, W(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form corner-sharing WO6 octahedra. The corner-sharing octahedral tilt angles are 13°. Bi(1) is bonded in a 6-coordinate geometry to six equivalent O(2) atoms. There are six inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Er(1) and one W(1) atom. In the second O site, O(2) is bonded to one W(2) and three equivalent Bi(1) atoms to form a mixture of corner and edge-sharing OBi3W tetrahedra. In the third O site, O(3) is bonded in a linear geometry to two equivalent W(2) atoms. In the fourth O site, O(4) is bonded in a linear geometry to two equivalent W(1) atoms. In the fifth O site, O(5) is bonded in a linear geometry to one Er(1) and one W(2) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to two equivalent Er(1) and one W(1) atom.
ErW2BiO9 crystallizes in the orthorhombic Pmmn space group. Er(1) is bonded in a 7-coordinate geometry to one O(1), two equivalent O(5), and four equivalent O(6) atoms. The Er(1)-O(1) bond length is 2.32 Å. Both Er(1)-O(5) bond lengths are 2.25 Å. All Er(1)-O(6) bond lengths are 2.36 Å. There are two inequivalent W sites. In the first W site, W(1) is bonded to one O(1), two equivalent O(4), and two equivalent O(6) atoms to form corner-sharing WO5 trigonal bipyramids. The W(1)-O(1) bond length is 1.81 Å. Both W(1)-O(4) bond lengths are 1.96 Å. Both W(1)-O(6) bond lengths are 1.85 Å. In the second W site, W(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form corner-sharing WO6 octahedra. The corner-sharing octahedral tilt angles are 13°. Both W(2)-O(2) bond lengths are 2.12 Å. Both W(2)-O(3) bond lengths are 1.97 Å. Both W(2)-O(5) bond lengths are 1.82 Å. Bi(1) is bonded in a 6-coordinate geometry to six equivalent O(2) atoms. There are two shorter (2.26 Å) and four longer (2.50 Å) Bi(1)-O(2) bond lengths. There are six inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Er(1) and one W(1) atom. In the second O site, O(2) is bonded to one W(2) and three equivalent Bi(1) atoms to form a mixture of corner and edge-sharing OBi3W tetrahedra. In the third O site, O(3) is bonded in a linear geometry to two equivalent W(2) atoms. In the fourth O site, O(4) is bonded in a linear geometry to two equivalent W(1) atoms. In the fifth O site, O(5) is bonded in a linear geometry to one Er(1) and one W(2) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to two equivalent Er(1) and one W(1) atom.