Ca5V3CO12 crystallizes in the hexagonal P6_3/m space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(2) atoms. In the second Ca site, Ca(2) is bonded to one C(1), one O(2), and four equivalent O(3) atoms to form distorted CaCO5 pentagonal pyramids that share corners with six equivalent Ca(2)CO5 pentagonal pyramids, corners with three equivalent V(1)O4 tetrahedra, and  an edgeedge with one V(1)O4 tetrahedra. V(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form VO4 tetrahedra that share corners with three equivalent Ca(2)CO5 pentagonal pyramids and  an edgeedge with one Ca(2)CO5 pentagonal pyramid. C(1) is bonded in a trigonal planar geometry to three equivalent Ca(2) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one V(1) atom. In the second O site, O(2) is bonded to one Ca(2), two equivalent Ca(1), and one V(1) atom to form distorted edge-sharing OCa3V tetrahedra. In the third O site, O(3) is bonded in a 3-coordinate geometry to two equivalent Ca(2) and one V(1) atom.
Ca5V3CO12 crystallizes in the hexagonal P6_3/m space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(2) atoms. All Ca(1)-O(1) bond lengths are 2.41 Å. All Ca(1)-O(2) bond lengths are 2.48 Å. In the second Ca site, Ca(2) is bonded to one C(1), one O(2), and four equivalent O(3) atoms to form distorted CaCO5 pentagonal pyramids that share corners with six equivalent Ca(2)CO5 pentagonal pyramids, corners with three equivalent V(1)O4 tetrahedra, and  an edgeedge with one V(1)O4 tetrahedra. The Ca(2)-C(1) bond length is 2.61 Å. The Ca(2)-O(2) bond length is 2.37 Å. There are two shorter (2.34 Å) and two longer (2.50 Å) Ca(2)-O(3) bond lengths. V(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form VO4 tetrahedra that share corners with three equivalent Ca(2)CO5 pentagonal pyramids and  an edgeedge with one Ca(2)CO5 pentagonal pyramid. The V(1)-O(1) bond length is 1.73 Å. The V(1)-O(2) bond length is 1.77 Å. Both V(1)-O(3) bond lengths are 1.74 Å. C(1) is bonded in a trigonal planar geometry to three equivalent Ca(2) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Ca(1) and one V(1) atom. In the second O site, O(2) is bonded to one Ca(2), two equivalent Ca(1), and one V(1) atom to form distorted edge-sharing OCa3V tetrahedra. In the third O site, O(3) is bonded in a 3-coordinate geometry to two equivalent Ca(2) and one V(1) atom.