K2SrNb5O15 crystallizes in the tetragonal P4bm space group. K(1) is bonded in a 7-coordinate geometry to one O(3), two equivalent O(4), and four equivalent O(2) atoms. Sr(1) is bonded to four equivalent O(1) and eight equivalent O(5) atoms to form SrO12 cuboctahedra that share faces with two equivalent Sr(1)O12 cuboctahedra and faces with eight equivalent Nb(2)O6 octahedra. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 0-33°. In the second Nb site, Nb(2) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(5) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra, corners with five equivalent Nb(2)O6 octahedra, and faces with two equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 10-34°. There are five inequivalent O sites. In the first O site, O(3) is bonded in a distorted linear geometry to two equivalent K(1) and two equivalent Nb(1) atoms. In the second O site, O(4) is bonded in a 4-coordinate geometry to two equivalent K(1) and two equivalent Nb(2) atoms. In the third O site, O(5) is bonded in a 2-coordinate geometry to two equivalent Sr(1) and two equivalent Nb(2) atoms. In the fourth O site, O(1) is bonded in a 3-coordinate geometry to one Sr(1) and two equivalent Nb(2) atoms. In the fifth O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1), one Nb(1), and one Nb(2) atom.
K2SrNb5O15 crystallizes in the tetragonal P4bm space group. K(1) is bonded in a 7-coordinate geometry to one O(3), two equivalent O(4), and four equivalent O(2) atoms. The K(1)-O(3) bond length is 3.08 Å. There is one shorter (2.84 Å) and one longer (3.00 Å) K(1)-O(4) bond length. There are two shorter (2.86 Å) and two longer (3.09 Å) K(1)-O(2) bond lengths. Sr(1) is bonded to four equivalent O(1) and eight equivalent O(5) atoms to form SrO12 cuboctahedra that share faces with two equivalent Sr(1)O12 cuboctahedra and faces with eight equivalent Nb(2)O6 octahedra. All Sr(1)-O(1) bond lengths are 2.71 Å. There are four shorter (2.70 Å) and four longer (2.92 Å) Sr(1)-O(5) bond lengths. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 0-33°. There is one shorter (1.86 Å) and one longer (2.20 Å) Nb(1)-O(3) bond length. All Nb(1)-O(2) bond lengths are 2.00 Å. In the second Nb site, Nb(2) is bonded to one O(2), one O(4), two equivalent O(1), and two equivalent O(5) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra, corners with five equivalent Nb(2)O6 octahedra, and faces with two equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 10-34°. The Nb(2)-O(2) bond length is 1.96 Å. The Nb(2)-O(4) bond length is 2.00 Å. There is one shorter (1.90 Å) and one longer (2.18 Å) Nb(2)-O(1) bond length. There is one shorter (2.02 Å) and one longer (2.07 Å) Nb(2)-O(5) bond length. There are five inequivalent O sites. In the first O site, O(3) is bonded in a distorted linear geometry to two equivalent K(1) and two equivalent Nb(1) atoms. In the second O site, O(4) is bonded in a 4-coordinate geometry to two equivalent K(1) and two equivalent Nb(2) atoms. In the third O site, O(5) is bonded in a 2-coordinate geometry to two equivalent Sr(1) and two equivalent Nb(2) atoms. In the fourth O site, O(1) is bonded in a 3-coordinate geometry to one Sr(1) and two equivalent Nb(2) atoms. In the fifth O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1), one Nb(1), and one Nb(2) atom.