TaNb2Zn2O8 crystallizes in the triclinic P-1 space group. Ta(1) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form TaO6 octahedra that share corners with four equivalent Nb(1)O6 octahedra, corners with four equivalent Nb(2)O6 octahedra, and edges with two equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 37-62°. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(8) atom to form NbO6 octahedra that share corners with four equivalent Ta(1)O6 octahedra and edges with two equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-62°. In the second Nb site, Nb(2) is bonded to one O(1), one O(2), one O(4), one O(5), one O(6), and one O(7) atom to form NbO6 octahedra that share corners with four equivalent Ta(1)O6 octahedra and edges with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 37-62°. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded in a distorted see-saw-like geometry to one O(5), one O(7), and two equivalent O(8) atoms. In the second Zn site, Zn(2) is bonded in a 5-coordinate geometry to one O(5), one O(6), one O(8), and two equivalent O(7) atoms. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ta(1), one Nb(1), and one Nb(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Ta(1), one Nb(1), and one Nb(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Ta(1) and one Nb(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Ta(1) and one Nb(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Nb(1), one Nb(2), one Zn(1), and one Zn(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Nb(1), one Nb(2), and one Zn(2) atom. In the seventh O site, O(7) is bonded to one Nb(2), one Zn(1), and two equivalent Zn(2) atoms to form a mixture of distorted corner and edge-sharing ONbZn3 trigonal pyramids. In the eighth O site, O(8) is bonded to one Nb(1), one Zn(2), and two equivalent Zn(1) atoms to form a mixture of corner and edge-sharing ONbZn3 trigonal pyramids.
TaNb2Zn2O8 crystallizes in the triclinic P-1 space group. Ta(1) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form TaO6 octahedra that share corners with four equivalent Nb(1)O6 octahedra, corners with four equivalent Nb(2)O6 octahedra, and edges with two equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 37-62°. The Ta(1)-O(1) bond length is 1.96 Å. The Ta(1)-O(2) bond length is 1.95 Å. There is one shorter (2.05 Å) and one longer (2.10 Å) Ta(1)-O(3) bond length. There is one shorter (2.01 Å) and one longer (2.18 Å) Ta(1)-O(4) bond length. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(8) atom to form NbO6 octahedra that share corners with four equivalent Ta(1)O6 octahedra and edges with two equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 42-62°. The Nb(1)-O(1) bond length is 2.23 Å. The Nb(1)-O(2) bond length is 2.15 Å. The Nb(1)-O(3) bond length is 2.11 Å. The Nb(1)-O(5) bond length is 2.03 Å. The Nb(1)-O(6) bond length is 2.03 Å. The Nb(1)-O(8) bond length is 2.14 Å. In the second Nb site, Nb(2) is bonded to one O(1), one O(2), one O(4), one O(5), one O(6), and one O(7) atom to form NbO6 octahedra that share corners with four equivalent Ta(1)O6 octahedra and edges with two equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 37-62°. The Nb(2)-O(1) bond length is 2.10 Å. The Nb(2)-O(2) bond length is 2.13 Å. The Nb(2)-O(4) bond length is 2.23 Å. The Nb(2)-O(5) bond length is 2.08 Å. The Nb(2)-O(6) bond length is 2.25 Å. The Nb(2)-O(7) bond length is 1.99 Å. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded in a distorted see-saw-like geometry to one O(5), one O(7), and two equivalent O(8) atoms. The Zn(1)-O(5) bond length is 1.97 Å. The Zn(1)-O(7) bond length is 1.97 Å. There is one shorter (1.98 Å) and one longer (2.09 Å) Zn(1)-O(8) bond length. In the second Zn site, Zn(2) is bonded in a 5-coordinate geometry to one O(5), one O(6), one O(8), and two equivalent O(7) atoms. The Zn(2)-O(5) bond length is 2.49 Å. The Zn(2)-O(6) bond length is 1.95 Å. The Zn(2)-O(8) bond length is 1.98 Å. There is one shorter (2.01 Å) and one longer (2.30 Å) Zn(2)-O(7) bond length. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ta(1), one Nb(1), and one Nb(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Ta(1), one Nb(1), and one Nb(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Ta(1) and one Nb(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Ta(1) and one Nb(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Nb(1), one Nb(2), one Zn(1), and one Zn(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Nb(1), one Nb(2), and one Zn(2) atom. In the seventh O site, O(7) is bonded to one Nb(2), one Zn(1), and two equivalent Zn(2) atoms to form a mixture of distorted corner and edge-sharing ONbZn3 trigonal pyramids. In the eighth O site, O(8) is bonded to one Nb(1), one Zn(2), and two equivalent Zn(1) atoms to form a mixture of corner and edge-sharing ONbZn3 trigonal pyramids.