Ca2P6O17 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), one O(12), one O(3), one O(5), one O(6), and one O(7) atom to form CaO6 octahedra that share  a cornercorner with one P(5)O4 tetrahedra,  a cornercorner with one P(6)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, corners with two equivalent P(4)O4 tetrahedra, and  an edgeedge with one Ca(2)O6 octahedra. In the second Ca site, Ca(2) is bonded to one O(10), one O(12), one O(13), one O(14), one O(4), and one O(5) atom to form CaO6 octahedra that share  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(6)O4 tetrahedra, and  an edgeedge with one Ca(1)O6 octahedra. There are six inequivalent P sites. In the first P site, P(1) is bonded to one O(10), one O(14), one O(17), and one O(2) atom to form PO4 tetrahedra that share corners with two equivalent Ca(2)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and  a cornercorner with one P(5)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 6-35°. In the second P site, P(2) is bonded to one O(11), one O(2), one O(4), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Ca(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, and  a cornercorner with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 27°. In the third P site, P(3) is bonded to one O(11), one O(3), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and  a cornercorner with one P(5)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 5-32°. In the fourth P site, P(4) is bonded to one O(15), one O(5), one O(6), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Ca(2)O6 octahedra, corners with two equivalent Ca(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and  a cornercorner with one P(6)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 31-59°. In the fifth P site, P(5) is bonded to one O(1), one O(16), one O(17), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, and  a cornercorner with one P(6)O4 tetrahedra. The corner-sharing octahedral tilt angles are 27°. In the sixth P site, P(6) is bonded to one O(12), one O(13), one O(15), and one O(16) atom to form PO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra, corners with two equivalent Ca(2)O6 octahedra,  a cornercorner with one P(4)O4 tetrahedra, and  a cornercorner with one P(5)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-62°. There are seventeen inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Ca(1) and one P(5) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Ca(1) and one P(3) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Ca(2) and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one P(4) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Ca(1) and one P(4) atom. In the seventh O site, O(7) is bonded in a linear geometry to one Ca(1) and one P(3) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one P(3) and one P(5) atom. In the ninth O site, O(9) is bonded in a bent 120 degrees geometry to one P(2) and one P(4) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Ca(2) and one P(1) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one P(2) and one P(3) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one P(6) atom. In the thirteenth O site, O(13) is bonded in a bent 150 degrees geometry to one Ca(2) and one P(6) atom. In the fourteenth O site, O(14) is bonded in a linear geometry to one Ca(2) and one P(1) atom. In the fifteenth O site, O(15) is bonded in a linear geometry to one P(4) and one P(6) atom. In the sixteenth O site, O(16) is bonded in a bent 120 degrees geometry to one P(5) and one P(6) atom. In the seventeenth O site, O(17) is bonded in a distorted bent 120 degrees geometry to one P(1) and one P(5) atom.
Ca2P6O17 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), one O(12), one O(3), one O(5), one O(6), and one O(7) atom to form CaO6 octahedra that share  a cornercorner with one P(5)O4 tetrahedra,  a cornercorner with one P(6)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, corners with two equivalent P(4)O4 tetrahedra, and  an edgeedge with one Ca(2)O6 octahedra. The Ca(1)-O(1) bond length is 2.32 Å. The Ca(1)-O(12) bond length is 2.46 Å. The Ca(1)-O(3) bond length is 2.30 Å. The Ca(1)-O(5) bond length is 2.40 Å. The Ca(1)-O(6) bond length is 2.32 Å. The Ca(1)-O(7) bond length is 2.26 Å. In the second Ca site, Ca(2) is bonded to one O(10), one O(12), one O(13), one O(14), one O(4), and one O(5) atom to form CaO6 octahedra that share  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(6)O4 tetrahedra, and  an edgeedge with one Ca(1)O6 octahedra. The Ca(2)-O(10) bond length is 2.29 Å. The Ca(2)-O(12) bond length is 2.41 Å. The Ca(2)-O(13) bond length is 2.30 Å. The Ca(2)-O(14) bond length is 2.27 Å. The Ca(2)-O(4) bond length is 2.33 Å. The Ca(2)-O(5) bond length is 2.43 Å. There are six inequivalent P sites. In the first P site, P(1) is bonded to one O(10), one O(14), one O(17), and one O(2) atom to form PO4 tetrahedra that share corners with two equivalent Ca(2)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and  a cornercorner with one P(5)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 6-35°. The P(1)-O(10) bond length is 1.47 Å. The P(1)-O(14) bond length is 1.47 Å. The P(1)-O(17) bond length is 1.62 Å. The P(1)-O(2) bond length is 1.62 Å. In the second P site, P(2) is bonded to one O(11), one O(2), one O(4), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Ca(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, and  a cornercorner with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 27°. The P(2)-O(11) bond length is 1.56 Å. The P(2)-O(2) bond length is 1.56 Å. The P(2)-O(4) bond length is 1.46 Å. The P(2)-O(9) bond length is 1.57 Å. In the third P site, P(3) is bonded to one O(11), one O(3), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and  a cornercorner with one P(5)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 5-32°. The P(3)-O(11) bond length is 1.62 Å. The P(3)-O(3) bond length is 1.47 Å. The P(3)-O(7) bond length is 1.47 Å. The P(3)-O(8) bond length is 1.62 Å. In the fourth P site, P(4) is bonded to one O(15), one O(5), one O(6), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Ca(2)O6 octahedra, corners with two equivalent Ca(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and  a cornercorner with one P(6)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 31-59°. The P(4)-O(15) bond length is 1.57 Å. The P(4)-O(5) bond length is 1.49 Å. The P(4)-O(6) bond length is 1.47 Å. The P(4)-O(9) bond length is 1.62 Å. In the fifth P site, P(5) is bonded to one O(1), one O(16), one O(17), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, and  a cornercorner with one P(6)O4 tetrahedra. The corner-sharing octahedral tilt angles are 27°. The P(5)-O(1) bond length is 1.46 Å. The P(5)-O(16) bond length is 1.57 Å. The P(5)-O(17) bond length is 1.56 Å. The P(5)-O(8) bond length is 1.56 Å. In the sixth P site, P(6) is bonded to one O(12), one O(13), one O(15), and one O(16) atom to form PO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra, corners with two equivalent Ca(2)O6 octahedra,  a cornercorner with one P(4)O4 tetrahedra, and  a cornercorner with one P(5)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-62°. The P(6)-O(12) bond length is 1.49 Å. The P(6)-O(13) bond length is 1.47 Å. The P(6)-O(15) bond length is 1.57 Å. The P(6)-O(16) bond length is 1.62 Å. There are seventeen inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Ca(1) and one P(5) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Ca(1) and one P(3) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Ca(2) and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one P(4) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Ca(1) and one P(4) atom. In the seventh O site, O(7) is bonded in a linear geometry to one Ca(1) and one P(3) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one P(3) and one P(5) atom. In the ninth O site, O(9) is bonded in a bent 120 degrees geometry to one P(2) and one P(4) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Ca(2) and one P(1) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one P(2) and one P(3) atom. In the twelfth O site, O(12) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one P(6) atom. In the thirteenth O site, O(13) is bonded in a bent 150 degrees geometry to one Ca(2) and one P(6) atom. In the fourteenth O site, O(14) is bonded in a linear geometry to one Ca(2) and one P(1) atom. In the fifteenth O site, O(15) is bonded in a linear geometry to one P(4) and one P(6) atom. In the sixteenth O site, O(16) is bonded in a bent 120 degrees geometry to one P(5) and one P(6) atom. In the seventeenth O site, O(17) is bonded in a distorted bent 120 degrees geometry to one P(1) and one P(5) atom.