Cs2U(Si2O5)3 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 11-coordinate geometry to one O(8), two equivalent O(10), two equivalent O(2), two equivalent O(4), two equivalent O(7), and two equivalent O(9) atoms. In the second Cs site, Cs(2) is bonded in a 5-coordinate geometry to one O(6), two equivalent O(2), and two equivalent O(4) atoms. U(1) is bonded to one O(1), one O(10), two equivalent O(4), and two equivalent O(7) atoms to form UO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form SiO4 tetrahedra that share  a cornercorner with one U(1)O6 octahedra,  a cornercorner with one Si(4)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 33°. In the second Si site, Si(2) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one U(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 48°. In the third Si site, Si(3) is bonded to one O(5), one O(7), one O(8), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one U(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 34°. In the fourth Si site, Si(4) is bonded to one O(10), one O(3), and two equivalent O(9) atoms to form SiO4 tetrahedra that share  a cornercorner with one U(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 29°. There are ten inequivalent O sites. In the first O site, O(10) is bonded in a bent 150 degrees geometry to two equivalent Cs(1), one U(1), and one Si(4) atom. In the second O site, O(1) is bonded in a bent 150 degrees geometry to one U(1) and one Si(1) atom. In the third O site, O(2) is bonded in a bent 150 degrees geometry to one Cs(1), one Cs(2), one Si(1), and one Si(2) atom. In the fourth O site, O(3) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(4) atom. In the fifth O site, O(4) is bonded in a 2-coordinate geometry to one Cs(1), one Cs(2), one U(1), and one Si(2) atom. In the sixth O site, O(5) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom. In the seventh O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Cs(2) and two equivalent Si(2) atoms. In the eighth O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Cs(1), one U(1), and one Si(3) atom. In the ninth O site, O(8) is bonded in a bent 150 degrees geometry to one Cs(1) and two equivalent Si(3) atoms. In the tenth O site, O(9) is bonded in a bent 150 degrees geometry to one Cs(1), one Si(3), and one Si(4) atom.
Cs2U(Si2O5)3 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 11-coordinate geometry to one O(8), two equivalent O(10), two equivalent O(2), two equivalent O(4), two equivalent O(7), and two equivalent O(9) atoms. The Cs(1)-O(8) bond length is 3.50 Å. Both Cs(1)-O(10) bond lengths are 3.70 Å. Both Cs(1)-O(2) bond lengths are 3.71 Å. Both Cs(1)-O(4) bond lengths are 3.32 Å. Both Cs(1)-O(7) bond lengths are 3.43 Å. Both Cs(1)-O(9) bond lengths are 3.36 Å. In the second Cs site, Cs(2) is bonded in a 5-coordinate geometry to one O(6), two equivalent O(2), and two equivalent O(4) atoms. The Cs(2)-O(6) bond length is 3.42 Å. Both Cs(2)-O(2) bond lengths are 3.44 Å. Both Cs(2)-O(4) bond lengths are 3.23 Å. U(1) is bonded to one O(1), one O(10), two equivalent O(4), and two equivalent O(7) atoms to form UO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. The U(1)-O(1) bond length is 2.24 Å. The U(1)-O(10) bond length is 2.26 Å. Both U(1)-O(4) bond lengths are 2.28 Å. Both U(1)-O(7) bond lengths are 2.26 Å. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form SiO4 tetrahedra that share  a cornercorner with one U(1)O6 octahedra,  a cornercorner with one Si(4)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 33°. The Si(1)-O(1) bond length is 1.60 Å. The Si(1)-O(3) bond length is 1.63 Å. Both Si(1)-O(2) bond lengths are 1.64 Å. In the second Si site, Si(2) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one U(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 48°. The Si(2)-O(2) bond length is 1.64 Å. The Si(2)-O(4) bond length is 1.62 Å. The Si(2)-O(5) bond length is 1.63 Å. The Si(2)-O(6) bond length is 1.64 Å. In the third Si site, Si(3) is bonded to one O(5), one O(7), one O(8), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one U(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 34°. The Si(3)-O(5) bond length is 1.64 Å. The Si(3)-O(7) bond length is 1.61 Å. The Si(3)-O(8) bond length is 1.65 Å. The Si(3)-O(9) bond length is 1.65 Å. In the fourth Si site, Si(4) is bonded to one O(10), one O(3), and two equivalent O(9) atoms to form SiO4 tetrahedra that share  a cornercorner with one U(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 29°. The Si(4)-O(10) bond length is 1.61 Å. The Si(4)-O(3) bond length is 1.63 Å. Both Si(4)-O(9) bond lengths are 1.65 Å. There are ten inequivalent O sites. In the first O site, O(10) is bonded in a bent 150 degrees geometry to two equivalent Cs(1), one U(1), and one Si(4) atom. In the second O site, O(1) is bonded in a bent 150 degrees geometry to one U(1) and one Si(1) atom. In the third O site, O(2) is bonded in a bent 150 degrees geometry to one Cs(1), one Cs(2), one Si(1), and one Si(2) atom. In the fourth O site, O(3) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(4) atom. In the fifth O site, O(4) is bonded in a 2-coordinate geometry to one Cs(1), one Cs(2), one U(1), and one Si(2) atom. In the sixth O site, O(5) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom. In the seventh O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Cs(2) and two equivalent Si(2) atoms. In the eighth O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Cs(1), one U(1), and one Si(3) atom. In the ninth O site, O(8) is bonded in a bent 150 degrees geometry to one Cs(1) and two equivalent Si(3) atoms. In the tenth O site, O(9) is bonded in a bent 150 degrees geometry to one Cs(1), one Si(3), and one Si(4) atom.