Ca2Nb2BiO8 crystallizes in the monoclinic C2/c space group. Ca(1) is bonded in a 6-coordinate geometry to three equivalent O(3) and three equivalent O(4) atoms. Nb(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form distorted NbO6 octahedra that share corners with four equivalent Bi(1)O6 octahedra and edges with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-57°. Bi(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form BiO6 octahedra that share corners with eight equivalent Nb(1)O6 octahedra and edges with two equivalent Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-57°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to two equivalent Nb(1) and one Bi(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Nb(1) and two equivalent Bi(1) atoms. In the third O site, O(3) is bonded in a 5-coordinate geometry to three equivalent Ca(1) and two equivalent Nb(1) atoms. In the fourth O site, O(4) is bonded to three equivalent Ca(1) and one Nb(1) atom to form a mixture of distorted corner and edge-sharing OCa3Nb trigonal pyramids.
Ca2Nb2BiO8 crystallizes in the monoclinic C2/c space group. Ca(1) is bonded in a 6-coordinate geometry to three equivalent O(3) and three equivalent O(4) atoms. There are a spread of Ca(1)-O(3) bond distances ranging from 2.26-2.83 Å. There are a spread of Ca(1)-O(4) bond distances ranging from 2.25-2.33 Å. Nb(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form distorted NbO6 octahedra that share corners with four equivalent Bi(1)O6 octahedra and edges with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-57°. The Nb(1)-O(2) bond length is 1.92 Å. The Nb(1)-O(4) bond length is 1.95 Å. There is one shorter (2.06 Å) and one longer (2.15 Å) Nb(1)-O(1) bond length. There is one shorter (2.06 Å) and one longer (2.34 Å) Nb(1)-O(3) bond length. Bi(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form BiO6 octahedra that share corners with eight equivalent Nb(1)O6 octahedra and edges with two equivalent Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-57°. Both Bi(1)-O(1) bond lengths are 2.33 Å. There are two shorter (2.36 Å) and two longer (2.63 Å) Bi(1)-O(2) bond lengths. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to two equivalent Nb(1) and one Bi(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Nb(1) and two equivalent Bi(1) atoms. In the third O site, O(3) is bonded in a 5-coordinate geometry to three equivalent Ca(1) and two equivalent Nb(1) atoms. In the fourth O site, O(4) is bonded to three equivalent Ca(1) and one Nb(1) atom to form a mixture of distorted corner and edge-sharing OCa3Nb trigonal pyramids.