NiB4O7 crystallizes in the orthorhombic Cmcm space group. Ni(1) is bonded to one O(1) and four equivalent O(3) atoms to form NiO5 square pyramids that share corners with four equivalent B(2)O4 tetrahedra and corners with six equivalent B(1)O4 tetrahedra. There are two inequivalent B sites. In the first B site, B(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form BO4 tetrahedra that share corners with three equivalent Ni(1)O5 square pyramids,  a cornercorner with one B(1)O4 tetrahedra, and corners with four equivalent B(2)O4 tetrahedra. In the second B site, B(2) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form BO4 tetrahedra that share corners with two equivalent Ni(1)O5 square pyramids, corners with two equivalent B(2)O4 tetrahedra, and corners with four equivalent B(1)O4 tetrahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Ni(1) and two equivalent B(1) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one B(1) and two equivalent B(2) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to one Ni(1), one B(1), and one B(2) atom.
NiB4O7 crystallizes in the orthorhombic Cmcm space group. Ni(1) is bonded to one O(1) and four equivalent O(3) atoms to form NiO5 square pyramids that share corners with four equivalent B(2)O4 tetrahedra and corners with six equivalent B(1)O4 tetrahedra. The Ni(1)-O(1) bond length is 2.09 Å. All Ni(1)-O(3) bond lengths are 2.03 Å. There are two inequivalent B sites. In the first B site, B(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form BO4 tetrahedra that share corners with three equivalent Ni(1)O5 square pyramids,  a cornercorner with one B(1)O4 tetrahedra, and corners with four equivalent B(2)O4 tetrahedra. The B(1)-O(1) bond length is 1.47 Å. The B(1)-O(2) bond length is 1.56 Å. Both B(1)-O(3) bond lengths are 1.45 Å. In the second B site, B(2) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form BO4 tetrahedra that share corners with two equivalent Ni(1)O5 square pyramids, corners with two equivalent B(2)O4 tetrahedra, and corners with four equivalent B(1)O4 tetrahedra. Both B(2)-O(2) bond lengths are 1.56 Å. Both B(2)-O(3) bond lengths are 1.45 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Ni(1) and two equivalent B(1) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one B(1) and two equivalent B(2) atoms. In the third O site, O(3) is bonded in a trigonal planar geometry to one Ni(1), one B(1), and one B(2) atom.