Ca2Nb2FeO8 crystallizes in the monoclinic C2/c space group. Ca(1) is bonded in a 8-coordinate geometry to one O(1), three equivalent O(4), and four equivalent O(3) atoms. Nb(1) is bonded in a 6-coordinate geometry to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms. Fe(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form edge-sharing FeO6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1), two equivalent Nb(1), and one Fe(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Nb(1) and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded in a 6-coordinate geometry to four 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 edge and corner-sharing OCa3Nb trigonal pyramids.
Ca2Nb2FeO8 crystallizes in the monoclinic C2/c space group. Ca(1) is bonded in a 8-coordinate geometry to one O(1), three equivalent O(4), and four equivalent O(3) atoms. The Ca(1)-O(1) bond length is 3.00 Å. There are a spread of Ca(1)-O(4) bond distances ranging from 2.20-2.36 Å. There are a spread of Ca(1)-O(3) bond distances ranging from 2.22-2.94 Å. Nb(1) is bonded in a 6-coordinate geometry to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms. The Nb(1)-O(2) bond length is 1.87 Å. The Nb(1)-O(4) bond length is 1.95 Å. There is one shorter (2.04 Å) and one longer (2.10 Å) Nb(1)-O(1) bond length. There is one shorter (2.05 Å) and one longer (2.34 Å) Nb(1)-O(3) bond length. Fe(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form edge-sharing FeO6 octahedra. Both Fe(1)-O(1) bond lengths are 2.23 Å. There are two shorter (2.16 Å) and two longer (2.34 Å) Fe(1)-O(2) bond lengths. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1), two equivalent Nb(1), and one Fe(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Nb(1) and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded in a 6-coordinate geometry to four 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 edge and corner-sharing OCa3Nb trigonal pyramids.