CaU2(PO9)2 crystallizes in the orthorhombic Pmm2 space group. Ca(1) is bonded in a 6-coordinate geometry to one O(5), one O(7), two equivalent O(10), and two equivalent O(9) atoms. There are two inequivalent U sites. In the first U site, U(1) is bonded to one O(5), one O(7), two equivalent O(1), and two equivalent O(2) atoms to form UO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(2)O4 tetrahedra. In the second U site, U(2) is bonded to one O(6), one O(8), two equivalent O(3), and two equivalent O(4) atoms to form UO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form PO4 tetrahedra that share corners with two equivalent U(1)O6 octahedra and corners with two equivalent U(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 35-38°. In the second P site, P(2) is bonded to two equivalent O(1) and two equivalent O(4) atoms to form PO4 tetrahedra that share corners with two equivalent U(1)O6 octahedra and corners with two equivalent U(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 34-37°. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one U(1) and one P(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one U(1) and one P(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one U(2) and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one U(2) and one P(2) atom. In the fifth O site, O(5) is bonded in a linear geometry to one Ca(1) and one U(1) atom. In the sixth O site, O(6) is bonded in a single-bond geometry to one U(2) atom. In the seventh O site, O(7) is bonded in a linear geometry to one Ca(1) and one U(1) atom. In the eighth O site, O(8) is bonded in a single-bond geometry to one U(2) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Ca(1), one O(9), and two equivalent O(11) atoms. In the tenth O site, O(10) is bonded in a linear geometry to one Ca(1) and one O(10) atom. In the eleventh O site, O(11) is bonded in a 2-coordinate geometry to two equivalent O(9) atoms.
CaU2(PO9)2 crystallizes in the orthorhombic Pmm2 space group. Ca(1) is bonded in a 6-coordinate geometry to one O(5), one O(7), two equivalent O(10), and two equivalent O(9) atoms. The Ca(1)-O(5) bond length is 2.19 Å. The Ca(1)-O(7) bond length is 2.19 Å. Both Ca(1)-O(10) bond lengths are 2.93 Å. Both Ca(1)-O(9) bond lengths are 2.94 Å. There are two inequivalent U sites. In the first U site, U(1) is bonded to one O(5), one O(7), two equivalent O(1), and two equivalent O(2) atoms to form UO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(2)O4 tetrahedra. The U(1)-O(5) bond length is 1.91 Å. The U(1)-O(7) bond length is 1.91 Å. Both U(1)-O(1) bond lengths are 2.21 Å. Both U(1)-O(2) bond lengths are 2.23 Å. In the second U site, U(2) is bonded to one O(6), one O(8), two equivalent O(3), and two equivalent O(4) atoms to form UO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(2)O4 tetrahedra. The U(2)-O(6) bond length is 1.83 Å. The U(2)-O(8) bond length is 1.81 Å. Both U(2)-O(3) bond lengths are 2.25 Å. Both U(2)-O(4) bond lengths are 2.27 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form PO4 tetrahedra that share corners with two equivalent U(1)O6 octahedra and corners with two equivalent U(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 35-38°. Both P(1)-O(2) bond lengths are 1.56 Å. Both P(1)-O(3) bond lengths are 1.54 Å. In the second P site, P(2) is bonded to two equivalent O(1) and two equivalent O(4) atoms to form PO4 tetrahedra that share corners with two equivalent U(1)O6 octahedra and corners with two equivalent U(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 34-37°. Both P(2)-O(1) bond lengths are 1.56 Å. Both P(2)-O(4) bond lengths are 1.54 Å. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one U(1) and one P(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one U(1) and one P(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one U(2) and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one U(2) and one P(2) atom. In the fifth O site, O(5) is bonded in a linear geometry to one Ca(1) and one U(1) atom. In the sixth O site, O(6) is bonded in a single-bond geometry to one U(2) atom. In the seventh O site, O(7) is bonded in a linear geometry to one Ca(1) and one U(1) atom. In the eighth O site, O(8) is bonded in a single-bond geometry to one U(2) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Ca(1), one O(9), and two equivalent O(11) atoms. The O(9)-O(9) bond length is 1.34 Å. Both O(9)-O(11) bond lengths are 1.78 Å. In the tenth O site, O(10) is bonded in a linear geometry to one Ca(1) and one O(10) atom. The O(10)-O(10) bond length is 1.22 Å. In the eleventh O site, O(11) is bonded in a 2-coordinate geometry to two equivalent O(9) atoms.