K2Ca2C2O3F2 crystallizes in the orthorhombic Cmc2_1 space group. K(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), and three equivalent F(1) atoms. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), two equivalent O(3), and two equivalent F(1) atoms to form distorted corner-sharing CaO3F2 trigonal bipyramids. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one C(2), one O(1), two equivalent O(2), and two equivalent F(1) atoms. There are two inequivalent C sites. In the first C site, C(1) is bonded in a bent 120 degrees geometry to one O(1) and one O(2) atom. In the second C site, C(2) is bonded in a distorted linear geometry to one Ca(2) and one O(3) atom. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent K(1), one Ca(1), one Ca(2), and one C(1) atom to form distorted OK2Ca2C trigonal bipyramids that share corners with two equivalent F(1)K3Ca2 trigonal bipyramids, corners with three equivalent O(2)K2Ca2C trigonal bipyramids,  an edgeedge with one O(2)K2Ca2C trigonal bipyramid, and edges with four equivalent F(1)K3Ca2 trigonal bipyramids. In the second O site, O(2) is bonded to two equivalent K(1), two equivalent Ca(2), and one C(1) atom to form distorted OK2Ca2C trigonal bipyramids that share corners with two equivalent O(2)K2Ca2C trigonal bipyramids, corners with two equivalent F(1)K3Ca2 trigonal bipyramids, corners with three equivalent O(1)K2Ca2C trigonal bipyramids,  an edgeedge with one O(1)K2Ca2C trigonal bipyramid, and edges with four equivalent F(1)K3Ca2 trigonal bipyramids. In the third O site, O(3) is bonded in a 5-coordinate geometry to two equivalent K(1), two equivalent Ca(1), and one C(2) atom. F(1) is bonded to three equivalent K(1), one Ca(1), and one Ca(2) atom to form FK3Ca2 trigonal bipyramids that share  a cornercorner with one O(1)K2Ca2C trigonal bipyramid,  a cornercorner with one O(2)K2Ca2C trigonal bipyramid, corners with eight equivalent F(1)K3Ca2 trigonal bipyramids, edges with two equivalent O(1)K2Ca2C trigonal bipyramids, and edges with two equivalent O(2)K2Ca2C trigonal bipyramids.
K2Ca2C2O3F2 crystallizes in the orthorhombic Cmc2_1 space group. K(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), and three equivalent F(1) atoms. The K(1)-O(1) bond length is 2.84 Å. The K(1)-O(2) bond length is 2.80 Å. The K(1)-O(3) bond length is 2.92 Å. There are a spread of K(1)-F(1) bond distances ranging from 2.76-2.82 Å. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), two equivalent O(3), and two equivalent F(1) atoms to form distorted corner-sharing CaO3F2 trigonal bipyramids. The Ca(1)-O(1) bond length is 2.35 Å. Both Ca(1)-O(3) bond lengths are 2.39 Å. Both Ca(1)-F(1) bond lengths are 2.28 Å. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one C(2), one O(1), two equivalent O(2), and two equivalent F(1) atoms. The Ca(2)-C(2) bond length is 2.46 Å. The Ca(2)-O(1) bond length is 2.45 Å. There is one shorter (2.37 Å) and one longer (2.55 Å) Ca(2)-O(2) bond length. Both Ca(2)-F(1) bond lengths are 2.34 Å. There are two inequivalent C sites. In the first C site, C(1) is bonded in a bent 120 degrees geometry to one O(1) and one O(2) atom. The C(1)-O(1) bond length is 1.31 Å. The C(1)-O(2) bond length is 1.32 Å. In the second C site, C(2) is bonded in a distorted linear geometry to one Ca(2) and one O(3) atom. The C(2)-O(3) bond length is 1.32 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent K(1), one Ca(1), one Ca(2), and one C(1) atom to form distorted OK2Ca2C trigonal bipyramids that share corners with two equivalent F(1)K3Ca2 trigonal bipyramids, corners with three equivalent O(2)K2Ca2C trigonal bipyramids,  an edgeedge with one O(2)K2Ca2C trigonal bipyramid, and edges with four equivalent F(1)K3Ca2 trigonal bipyramids. In the second O site, O(2) is bonded to two equivalent K(1), two equivalent Ca(2), and one C(1) atom to form distorted OK2Ca2C trigonal bipyramids that share corners with two equivalent O(2)K2Ca2C trigonal bipyramids, corners with two equivalent F(1)K3Ca2 trigonal bipyramids, corners with three equivalent O(1)K2Ca2C trigonal bipyramids,  an edgeedge with one O(1)K2Ca2C trigonal bipyramid, and edges with four equivalent F(1)K3Ca2 trigonal bipyramids. In the third O site, O(3) is bonded in a 5-coordinate geometry to two equivalent K(1), two equivalent Ca(1), and one C(2) atom. F(1) is bonded to three equivalent K(1), one Ca(1), and one Ca(2) atom to form FK3Ca2 trigonal bipyramids that share  a cornercorner with one O(1)K2Ca2C trigonal bipyramid,  a cornercorner with one O(2)K2Ca2C trigonal bipyramid, corners with eight equivalent F(1)K3Ca2 trigonal bipyramids, edges with two equivalent O(1)K2Ca2C trigonal bipyramids, and edges with two equivalent O(2)K2Ca2C trigonal bipyramids.