Ca2TaMoO6 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to one O(3), one O(4), two equivalent O(2), and four equivalent O(1) atoms. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to one O(3), one O(4), two equivalent O(1), and four equivalent O(2) atoms. Ta(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra and corners with four equivalent Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 31-32°. Mo(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form MoO6 octahedra that share corners with two equivalent Mo(1)O6 octahedra and corners with four equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 32-40°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Ca(2), two equivalent Ca(1), one Ta(1), and one Mo(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Ca(1), two equivalent Ca(2), one Ta(1), and one Mo(1) atom. In the third O site, O(3) is bonded to one Ca(1), one Ca(2), and two equivalent Ta(1) atoms to form distorted OCa2Ta2 tetrahedra that share corners with two equivalent O(4)Ca2Mo2 tetrahedra and corners with two equivalent O(3)Ca2Ta2 tetrahedra. In the fourth O site, O(4) is bonded to one Ca(1), one Ca(2), and two equivalent Mo(1) atoms to form OCa2Mo2 tetrahedra that share corners with two equivalent O(4)Ca2Mo2 tetrahedra and corners with two equivalent O(3)Ca2Ta2 tetrahedra.
Ca2TaMoO6 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to one O(3), one O(4), two equivalent O(2), and four equivalent O(1) atoms. The Ca(1)-O(3) bond length is 2.50 Å. The Ca(1)-O(4) bond length is 2.24 Å. Both Ca(1)-O(2) bond lengths are 2.71 Å. There are two shorter (2.38 Å) and two longer (2.82 Å) Ca(1)-O(1) bond lengths. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to one O(3), one O(4), two equivalent O(1), and four equivalent O(2) atoms. The Ca(2)-O(3) bond length is 2.39 Å. The Ca(2)-O(4) bond length is 2.35 Å. Both Ca(2)-O(1) bond lengths are 2.65 Å. There are two shorter (2.42 Å) and two longer (2.78 Å) Ca(2)-O(2) bond lengths. Ta(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra and corners with four equivalent Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 31-32°. Both Ta(1)-O(1) bond lengths are 1.98 Å. Both Ta(1)-O(2) bond lengths are 1.99 Å. Both Ta(1)-O(3) bond lengths are 2.06 Å. Mo(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form MoO6 octahedra that share corners with two equivalent Mo(1)O6 octahedra and corners with four equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 32-40°. Both Mo(1)-O(1) bond lengths are 2.17 Å. Both Mo(1)-O(2) bond lengths are 2.18 Å. Both Mo(1)-O(4) bond lengths are 2.11 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Ca(2), two equivalent Ca(1), one Ta(1), and one Mo(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Ca(1), two equivalent Ca(2), one Ta(1), and one Mo(1) atom. In the third O site, O(3) is bonded to one Ca(1), one Ca(2), and two equivalent Ta(1) atoms to form distorted OCa2Ta2 tetrahedra that share corners with two equivalent O(4)Ca2Mo2 tetrahedra and corners with two equivalent O(3)Ca2Ta2 tetrahedra. In the fourth O site, O(4) is bonded to one Ca(1), one Ca(2), and two equivalent Mo(1) atoms to form OCa2Mo2 tetrahedra that share corners with two equivalent O(4)Ca2Mo2 tetrahedra and corners with two equivalent O(3)Ca2Ta2 tetrahedra.