K2LaTa5O15 crystallizes in the tetragonal P4/mbm space group. K(1) is bonded in a 9-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(3), and four equivalent O(4) atoms. La(1) is bonded to four equivalent O(3) and eight equivalent O(5) atoms to form LaO12 cuboctahedra that share faces with two equivalent La(1)O12 cuboctahedra and faces with eight equivalent Ta(2)O6 octahedra. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(1) and four equivalent O(4) atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 0-32°. In the second Ta site, Ta(2) is bonded to one O(2), one O(4), two equivalent O(3), and two equivalent O(5) atoms to form TaO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra, corners with five equivalent Ta(2)O6 octahedra, and faces with two equivalent La(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 10-36°. There are five inequivalent O sites. In the first O site, O(5) is bonded in a distorted linear geometry to two equivalent La(1) and two equivalent Ta(2) atoms. In the second O site, O(1) is bonded in a linear geometry to two equivalent K(1) and two equivalent Ta(1) atoms. In the third O site, O(2) is bonded in a 4-coordinate geometry to two equivalent K(1) and two equivalent Ta(2) atoms. In the fourth O site, O(3) is bonded in a 2-coordinate geometry to one K(1), one La(1), and two equivalent Ta(2) atoms. In the fifth O site, O(4) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1), one Ta(1), and one Ta(2) atom.
K2LaTa5O15 crystallizes in the tetragonal P4/mbm space group. K(1) is bonded in a 9-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(3), and four equivalent O(4) atoms. The K(1)-O(1) bond length is 3.07 Å. Both K(1)-O(2) bond lengths are 2.85 Å. Both K(1)-O(3) bond lengths are 3.24 Å. All K(1)-O(4) bond lengths are 2.92 Å. La(1) is bonded to four equivalent O(3) and eight equivalent O(5) atoms to form LaO12 cuboctahedra that share faces with two equivalent La(1)O12 cuboctahedra and faces with eight equivalent Ta(2)O6 octahedra. All La(1)-O(3) bond lengths are 2.68 Å. All La(1)-O(5) bond lengths are 2.72 Å. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(1) and four equivalent O(4) atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 0-32°. Both Ta(1)-O(1) bond lengths are 1.98 Å. All Ta(1)-O(4) bond lengths are 2.00 Å. In the second Ta site, Ta(2) is bonded to one O(2), one O(4), two equivalent O(3), and two equivalent O(5) atoms to form TaO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra, corners with five equivalent Ta(2)O6 octahedra, and faces with two equivalent La(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 10-36°. The Ta(2)-O(2) bond length is 1.99 Å. The Ta(2)-O(4) bond length is 1.91 Å. Both Ta(2)-O(3) bond lengths are 1.99 Å. There is one shorter (2.04 Å) and one longer (2.07 Å) Ta(2)-O(5) bond length. There are five inequivalent O sites. In the first O site, O(5) is bonded in a distorted linear geometry to two equivalent La(1) and two equivalent Ta(2) atoms. In the second O site, O(1) is bonded in a linear geometry to two equivalent K(1) and two equivalent Ta(1) atoms. In the third O site, O(2) is bonded in a 4-coordinate geometry to two equivalent K(1) and two equivalent Ta(2) atoms. In the fourth O site, O(3) is bonded in a 2-coordinate geometry to one K(1), one La(1), and two equivalent Ta(2) atoms. In the fifth O site, O(4) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1), one Ta(1), and one Ta(2) atom.