Ag2Nb4O11 crystallizes in the trigonal R3c space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to three equivalent O(1) and three equivalent O(5) atoms to form NbO6 octahedra that share corners with six equivalent Nb(2)O7 pentagonal bipyramids and edges with three equivalent Ag(2)O6 octahedra. In the second Nb site, Nb(2) is bonded to one O(1), one O(2), one O(3), one O(5), and three equivalent O(4) atoms to form distorted NbO7 pentagonal bipyramids that share corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Ag(2)O6 octahedra, corners with two equivalent Nb(2)O7 pentagonal bipyramids, and edges with four equivalent Nb(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 39-75°. There are two inequivalent Ag sites. In the first Ag site, Ag(1) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(5) atoms. In the second Ag site, Ag(2) is bonded to three equivalent O(1) and three equivalent O(5) atoms to form distorted AgO6 octahedra that share corners with six equivalent Nb(2)O7 pentagonal bipyramids and edges with three equivalent Nb(1)O6 octahedra. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Nb(1), one Nb(2), one Ag(1), and one Ag(2) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to three equivalent Nb(2) atoms. In the third O site, O(3) is bonded in a trigonal non-coplanar geometry to three equivalent Nb(2) atoms. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to three equivalent Nb(2) atoms. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Nb(1), one Nb(2), one Ag(1), and one Ag(2) atom.
Ag2Nb4O11 crystallizes in the trigonal R3c space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to three equivalent O(1) and three equivalent O(5) atoms to form NbO6 octahedra that share corners with six equivalent Nb(2)O7 pentagonal bipyramids and edges with three equivalent Ag(2)O6 octahedra. All Nb(1)-O(1) bond lengths are 2.16 Å. All Nb(1)-O(5) bond lengths are 1.92 Å. In the second Nb site, Nb(2) is bonded to one O(1), one O(2), one O(3), one O(5), and three equivalent O(4) atoms to form distorted NbO7 pentagonal bipyramids that share corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Ag(2)O6 octahedra, corners with two equivalent Nb(2)O7 pentagonal bipyramids, and edges with four equivalent Nb(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 39-75°. The Nb(2)-O(1) bond length is 1.89 Å. The Nb(2)-O(2) bond length is 2.03 Å. The Nb(2)-O(3) bond length is 2.05 Å. The Nb(2)-O(5) bond length is 2.17 Å. There are two shorter (2.05 Å) and one longer (2.36 Å) Nb(2)-O(4) bond length. There are two inequivalent Ag sites. In the first Ag site, Ag(1) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(5) atoms. All Ag(1)-O(1) bond lengths are 2.67 Å. All Ag(1)-O(5) bond lengths are 2.60 Å. In the second Ag site, Ag(2) is bonded to three equivalent O(1) and three equivalent O(5) atoms to form distorted AgO6 octahedra that share corners with six equivalent Nb(2)O7 pentagonal bipyramids and edges with three equivalent Nb(1)O6 octahedra. All Ag(2)-O(1) bond lengths are 2.75 Å. All Ag(2)-O(5) bond lengths are 2.54 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Nb(1), one Nb(2), one Ag(1), and one Ag(2) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to three equivalent Nb(2) atoms. In the third O site, O(3) is bonded in a trigonal non-coplanar geometry to three equivalent Nb(2) atoms. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to three equivalent Nb(2) atoms. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Nb(1), one Nb(2), one Ag(1), and one Ag(2) atom.