CsNbV2O8 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 10-coordinate geometry to one O(10), two equivalent O(11), two equivalent O(3), two equivalent O(7), and three equivalent O(9) atoms. In the second Cs site, Cs(2) is bonded in a 11-coordinate geometry to one O(2), one O(4), two equivalent O(1), two equivalent O(12), two equivalent O(5), and three equivalent O(8) atoms. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra, corners with two equivalent V(4)O4 tetrahedra, and corners with three equivalent V(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 17°. In the second Nb site, Nb(2) is bonded to one O(4), one O(6), two equivalent O(5), and two equivalent O(7) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra, corners with two equivalent V(3)O4 tetrahedra, and corners with three equivalent V(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 17°. There are four inequivalent V sites. In the first V site, V(1) is bonded to one O(2), one O(8), and two equivalent O(1) atoms to form VO4 tetrahedra that share corners with three equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-30°. In the second V site, V(2) is bonded to one O(6), one O(9), and two equivalent O(7) atoms to form VO4 tetrahedra that share corners with three equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-23°. In the third V site, V(3) is bonded to one O(10), one O(11), and two equivalent O(5) atoms to form VO4 tetrahedra that share corners with two equivalent Nb(2)O6 octahedra and  a cornercorner with one V(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 34°. In the fourth V site, V(4) is bonded to one O(11), one O(12), and two equivalent O(3) atoms to form VO4 tetrahedra that share corners with two equivalent Nb(1)O6 octahedra and  a cornercorner with one V(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 30°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Cs(2), one Nb(1), and one V(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Cs(2), one Nb(1), and one V(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Cs(1), one Nb(1), and one V(4) atom. In the fourth O site, O(4) is bonded in a distorted linear geometry to one Cs(2), one Nb(1), and one Nb(2) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Cs(2), one Nb(2), and one V(3) atom. In the sixth O site, O(6) is bonded in a linear geometry to one Nb(2) and one V(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Cs(1), one Nb(2), and one V(2) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to three equivalent Cs(2) and one V(1) atom. In the ninth O site, O(9) is bonded in a distorted single-bond geometry to three equivalent Cs(1) and one V(2) atom. In the tenth O site, O(10) is bonded in a single-bond geometry to one Cs(1) and one V(3) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to two equivalent Cs(1), one V(3), and one V(4) atom. In the twelfth O site, O(12) is bonded in a single-bond geometry to two equivalent Cs(2) and one V(4) atom.
CsNbV2O8 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 10-coordinate geometry to one O(10), two equivalent O(11), two equivalent O(3), two equivalent O(7), and three equivalent O(9) atoms. The Cs(1)-O(10) bond length is 3.32 Å. Both Cs(1)-O(11) bond lengths are 3.49 Å. Both Cs(1)-O(3) bond lengths are 3.42 Å. Both Cs(1)-O(7) bond lengths are 3.37 Å. There is one shorter (3.13 Å) and two longer (3.19 Å) Cs(1)-O(9) bond lengths. In the second Cs site, Cs(2) is bonded in a 11-coordinate geometry to one O(2), one O(4), two equivalent O(1), two equivalent O(12), two equivalent O(5), and three equivalent O(8) atoms. The Cs(2)-O(2) bond length is 3.69 Å. The Cs(2)-O(4) bond length is 3.58 Å. Both Cs(2)-O(1) bond lengths are 3.69 Å. Both Cs(2)-O(12) bond lengths are 3.49 Å. Both Cs(2)-O(5) bond lengths are 3.50 Å. There is one shorter (3.15 Å) and two longer (3.29 Å) Cs(2)-O(8) bond lengths. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(3) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra, corners with two equivalent V(4)O4 tetrahedra, and corners with three equivalent V(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 17°. The Nb(1)-O(2) bond length is 2.06 Å. The Nb(1)-O(4) bond length is 1.96 Å. Both Nb(1)-O(1) bond lengths are 1.97 Å. Both Nb(1)-O(3) bond lengths are 2.03 Å. In the second Nb site, Nb(2) is bonded to one O(4), one O(6), two equivalent O(5), and two equivalent O(7) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra, corners with two equivalent V(3)O4 tetrahedra, and corners with three equivalent V(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 17°. The Nb(2)-O(4) bond length is 1.95 Å. The Nb(2)-O(6) bond length is 2.05 Å. Both Nb(2)-O(5) bond lengths are 2.05 Å. Both Nb(2)-O(7) bond lengths are 1.97 Å. There are four inequivalent V sites. In the first V site, V(1) is bonded to one O(2), one O(8), and two equivalent O(1) atoms to form VO4 tetrahedra that share corners with three equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-30°. The V(1)-O(2) bond length is 1.75 Å. The V(1)-O(8) bond length is 1.66 Å. Both V(1)-O(1) bond lengths are 1.78 Å. In the second V site, V(2) is bonded to one O(6), one O(9), and two equivalent O(7) atoms to form VO4 tetrahedra that share corners with three equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-23°. The V(2)-O(6) bond length is 1.74 Å. The V(2)-O(9) bond length is 1.66 Å. Both V(2)-O(7) bond lengths are 1.79 Å. In the third V site, V(3) is bonded to one O(10), one O(11), and two equivalent O(5) atoms to form VO4 tetrahedra that share corners with two equivalent Nb(2)O6 octahedra and  a cornercorner with one V(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 34°. The V(3)-O(10) bond length is 1.64 Å. The V(3)-O(11) bond length is 1.83 Å. Both V(3)-O(5) bond lengths are 1.77 Å. In the fourth V site, V(4) is bonded to one O(11), one O(12), and two equivalent O(3) atoms to form VO4 tetrahedra that share corners with two equivalent Nb(1)O6 octahedra and  a cornercorner with one V(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 30°. The V(4)-O(11) bond length is 1.81 Å. The V(4)-O(12) bond length is 1.64 Å. Both V(4)-O(3) bond lengths are 1.77 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to one Cs(2), one Nb(1), and one V(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Cs(2), one Nb(1), and one V(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Cs(1), one Nb(1), and one V(4) atom. In the fourth O site, O(4) is bonded in a distorted linear geometry to one Cs(2), one Nb(1), and one Nb(2) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Cs(2), one Nb(2), and one V(3) atom. In the sixth O site, O(6) is bonded in a linear geometry to one Nb(2) and one V(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Cs(1), one Nb(2), and one V(2) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to three equivalent Cs(2) and one V(1) atom. In the ninth O site, O(9) is bonded in a distorted single-bond geometry to three equivalent Cs(1) and one V(2) atom. In the tenth O site, O(10) is bonded in a single-bond geometry to one Cs(1) and one V(3) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to two equivalent Cs(1), one V(3), and one V(4) atom. In the twelfth O site, O(12) is bonded in a single-bond geometry to two equivalent Cs(2) and one V(4) atom.