KCa7Si3(O4F)3 crystallizes in the trigonal P31c space group. K(1) is bonded in a 9-coordinate geometry to three equivalent O(1), three equivalent O(2), and three equivalent F(1) atoms. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to six equivalent O(4) atoms to form distorted CaO6 pentagonal pyramids that share corners with six equivalent Si(1)O4 tetrahedra and faces with two equivalent Ca(1)O6 pentagonal pyramids. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent F(1) atoms. In the third Ca site, Ca(3) is bonded in a 8-coordinate geometry to one O(1), one O(4), two equivalent O(2), two equivalent O(3), and two equivalent F(1) atoms. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent Ca(1)O6 pentagonal pyramids. There are four inequivalent O sites. In the first O site, O(3) is bonded in a 1-coordinate geometry to two equivalent Ca(2), two equivalent Ca(3), and one Si(1) atom. In the second O site, O(4) is bonded to one Ca(3), two equivalent Ca(1), and one Si(1) atom to form distorted OCa3Si tetrahedra that share corners with two equivalent F(1)KCa4 square pyramids, corners with six equivalent O(4)Ca3Si tetrahedra, and edges with two equivalent O(4)Ca3Si tetrahedra. In the third O site, O(1) is bonded in a 4-coordinate geometry to one K(1), one Ca(3), two equivalent Ca(2), and one Si(1) atom. In the fourth O site, O(2) is bonded in a 6-coordinate geometry to one K(1), two equivalent Ca(2), two equivalent Ca(3), and one Si(1) atom. F(1) is bonded to one K(1), two equivalent Ca(2), and two equivalent Ca(3) atoms to form FKCa4 square pyramids that share corners with two equivalent F(1)KCa4 square pyramids, corners with two equivalent O(4)Ca3Si tetrahedra, and edges with two equivalent F(1)KCa4 square pyramids.
KCa7Si3(O4F)3 crystallizes in the trigonal P31c space group. K(1) is bonded in a 9-coordinate geometry to three equivalent O(1), three equivalent O(2), and three equivalent F(1) atoms. All K(1)-O(1) bond lengths are 3.15 Å. All K(1)-O(2) bond lengths are 2.87 Å. All K(1)-F(1) bond lengths are 2.68 Å. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to six equivalent O(4) atoms to form distorted CaO6 pentagonal pyramids that share corners with six equivalent Si(1)O4 tetrahedra and faces with two equivalent Ca(1)O6 pentagonal pyramids. There are three shorter (2.38 Å) and three longer (2.45 Å) Ca(1)-O(4) bond lengths. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent F(1) atoms. There is one shorter (2.33 Å) and one longer (2.41 Å) Ca(2)-O(1) bond length. There is one shorter (2.31 Å) and one longer (2.78 Å) Ca(2)-O(2) bond length. There is one shorter (2.48 Å) and one longer (2.91 Å) Ca(2)-O(3) bond length. There is one shorter (2.32 Å) and one longer (2.36 Å) Ca(2)-F(1) bond length. In the third Ca site, Ca(3) is bonded in a 8-coordinate geometry to one O(1), one O(4), two equivalent O(2), two equivalent O(3), and two equivalent F(1) atoms. The Ca(3)-O(1) bond length is 2.33 Å. The Ca(3)-O(4) bond length is 2.42 Å. There is one shorter (2.66 Å) and one longer (2.74 Å) Ca(3)-O(2) bond length. There is one shorter (2.60 Å) and one longer (2.74 Å) Ca(3)-O(3) bond length. There is one shorter (2.39 Å) and one longer (2.54 Å) Ca(3)-F(1) bond length. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent Ca(1)O6 pentagonal pyramids. The Si(1)-O(1) bond length is 1.65 Å. The Si(1)-O(2) bond length is 1.65 Å. The Si(1)-O(3) bond length is 1.65 Å. The Si(1)-O(4) bond length is 1.66 Å. There are four inequivalent O sites. In the first O site, O(3) is bonded in a 1-coordinate geometry to two equivalent Ca(2), two equivalent Ca(3), and one Si(1) atom. In the second O site, O(4) is bonded to one Ca(3), two equivalent Ca(1), and one Si(1) atom to form distorted OCa3Si tetrahedra that share corners with two equivalent F(1)KCa4 square pyramids, corners with six equivalent O(4)Ca3Si tetrahedra, and edges with two equivalent O(4)Ca3Si tetrahedra. In the third O site, O(1) is bonded in a 4-coordinate geometry to one K(1), one Ca(3), two equivalent Ca(2), and one Si(1) atom. In the fourth O site, O(2) is bonded in a 6-coordinate geometry to one K(1), two equivalent Ca(2), two equivalent Ca(3), and one Si(1) atom. F(1) is bonded to one K(1), two equivalent Ca(2), and two equivalent Ca(3) atoms to form FKCa4 square pyramids that share corners with two equivalent F(1)KCa4 square pyramids, corners with two equivalent O(4)Ca3Si tetrahedra, and edges with two equivalent F(1)KCa4 square pyramids.