Tl(La2Sr2)Ni2O9 crystallizes in the orthorhombic Aem2 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 9-coordinate geometry to one O(1), four equivalent O(4), and four equivalent O(6) atoms. In the second Sr site, Sr(2) is bonded in a 9-coordinate geometry to one O(1), four equivalent O(5), and four equivalent O(7) atoms. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 9-coordinate geometry to four equivalent O(6) and five equivalent O(2) atoms. In the second La site, La(2) is bonded in a 9-coordinate geometry to four equivalent O(7) and five equivalent O(3) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(3), one O(5), and four equivalent O(7) atoms to form NiO6 octahedra that share corners with four equivalent Ni(1)O6 octahedra and  a cornercorner with one Tl(1)O5 square pyramid. The corner-sharing octahedral tilt angles are 4°. In the second Ni site, Ni(2) is bonded to one O(2), one O(4), and four equivalent O(6) atoms to form NiO6 octahedra that share corners with four equivalent Ni(2)O6 octahedra and  a cornercorner with one Tl(1)O5 square pyramid. The corner-sharing octahedral tilt angles are 4°. Tl(1) is bonded to one O(4), one O(5), and three equivalent O(1) atoms to form distorted TlO5 square pyramids that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one Ni(2)O6 octahedra, and corners with six equivalent Tl(1)O5 square pyramids. The corner-sharing octahedral tilt angles are 8°. There are seven inequivalent O sites. In the first O site, O(4) is bonded to four equivalent Sr(1), one Ni(2), and one Tl(1) atom to form distorted OSr4TlNi octahedra that share  a cornercorner with one O(2)La5Ni octahedra,  a cornercorner with one O(5)Sr4TlNi octahedra, corners with four equivalent O(4)Sr4TlNi octahedra, corners with eight equivalent O(6)Sr2La2Ni2 octahedra,  a cornercorner with one O(1)Sr2Tl3 square pyramid, edges with four equivalent O(4)Sr4TlNi octahedra, edges with three equivalent O(1)Sr2Tl3 square pyramids, and faces with four equivalent O(6)Sr2La2Ni2 octahedra. The corner-sharing octahedral tilt angles range from 2-55°. In the second O site, O(5) is bonded to four equivalent Sr(2), one Ni(1), and one Tl(1) atom to form distorted OSr4TlNi octahedra that share  a cornercorner with one O(3)La5Ni octahedra,  a cornercorner with one O(4)Sr4TlNi octahedra, corners with four equivalent O(5)Sr4TlNi octahedra, corners with eight equivalent O(7)Sr2La2Ni2 octahedra,  a cornercorner with one O(1)Sr2Tl3 square pyramid, edges with four equivalent O(5)Sr4TlNi octahedra, edges with three equivalent O(1)Sr2Tl3 square pyramids, and faces with four equivalent O(7)Sr2La2Ni2 octahedra. The corner-sharing octahedral tilt angles range from 1-54°. In the third O site, O(6) is bonded to two equivalent Sr(1), two equivalent La(1), and two equivalent Ni(2) atoms to form distorted OSr2La2Ni2 octahedra that share corners with two equivalent O(6)Sr2La2Ni2 octahedra, corners with four equivalent O(4)Sr4TlNi octahedra, corners with six equivalent O(2)La5Ni octahedra, corners with two equivalent O(1)Sr2Tl3 square pyramids, edges with two equivalent O(6)Sr2La2Ni2 octahedra, faces with two equivalent O(2)La5Ni octahedra, faces with two equivalent O(4)Sr4TlNi octahedra, and faces with four equivalent O(6)Sr2La2Ni2 octahedra. The corner-sharing octahedral tilt angles range from 4-55°. In the fourth O site, O(7) is bonded to two equivalent Sr(2), two equivalent La(2), and two equivalent Ni(1) atoms to form distorted OSr2La2Ni2 octahedra that share corners with two equivalent O(7)Sr2La2Ni2 octahedra, corners with four equivalent O(5)Sr4TlNi octahedra, corners with six equivalent O(3)La5Ni octahedra, corners with two equivalent O(1)Sr2Tl3 square pyramids, edges with two equivalent O(7)Sr2La2Ni2 octahedra, faces with two equivalent O(3)La5Ni octahedra, faces with two equivalent O(5)Sr4TlNi octahedra, and faces with four equivalent O(7)Sr2La2Ni2 octahedra. The corner-sharing octahedral tilt angles range from 4-54°. In the fifth O site, O(1) is bonded to one Sr(1), one Sr(2), and three equivalent Tl(1) atoms to form distorted OSr2Tl3 square pyramids that share  a cornercorner with one O(4)Sr4TlNi octahedra,  a cornercorner with one O(5)Sr4TlNi octahedra, corners with four equivalent O(6)Sr2La2Ni2 octahedra, corners with four equivalent O(7)Sr2La2Ni2 octahedra, corners with six equivalent O(1)Sr2Tl3 square pyramids, edges with three equivalent O(4)Sr4TlNi octahedra, and edges with three equivalent O(5)Sr4TlNi octahedra. The corner-sharing octahedral tilt angles range from 42-94°. In the sixth O site, O(2) is bonded to five equivalent La(1) and one Ni(2) atom to form distorted OLa5Ni octahedra that share  a cornercorner with one O(4)Sr4TlNi octahedra, corners with four equivalent O(2)La5Ni octahedra, corners with twelve equivalent O(6)Sr2La2Ni2 octahedra, edges with eight equivalent O(2)La5Ni octahedra, and faces with four equivalent O(6)Sr2La2Ni2 octahedra. The corner-sharing octahedral tilt angles range from 2-50°. In the seventh O site, O(3) is bonded to five equivalent La(2) and one Ni(1) atom to form distorted OLa5Ni octahedra that share  a cornercorner with one O(5)Sr4TlNi octahedra, corners with four equivalent O(3)La5Ni octahedra, corners with twelve equivalent O(7)Sr2La2Ni2 octahedra, edges with eight equivalent O(3)La5Ni octahedra, and faces with four equivalent O(7)Sr2La2Ni2 octahedra. The corner-sharing octahedral tilt angles range from 1-50°.
Tl(La2Sr2)Ni2O9 crystallizes in the orthorhombic Aem2 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 9-coordinate geometry to one O(1), four equivalent O(4), and four equivalent O(6) atoms. The Sr(1)-O(1) bond length is 2.51 Å. There are a spread of Sr(1)-O(4) bond distances ranging from 2.70-2.84 Å. There are two shorter (2.71 Å) and two longer (2.72 Å) Sr(1)-O(6) bond lengths. In the second Sr site, Sr(2) is bonded in a 9-coordinate geometry to one O(1), four equivalent O(5), and four equivalent O(7) atoms. The Sr(2)-O(1) bond length is 2.52 Å. There are a spread of Sr(2)-O(5) bond distances ranging from 2.70-2.84 Å. There are two shorter (2.71 Å) and two longer (2.73 Å) Sr(2)-O(7) bond lengths. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 9-coordinate geometry to four equivalent O(6) and five equivalent O(2) atoms. All La(1)-O(6) bond lengths are 2.54 Å. There are a spread of La(1)-O(2) bond distances ranging from 2.38-2.79 Å. In the second La site, La(2) is bonded in a 9-coordinate geometry to four equivalent O(7) and five equivalent O(3) atoms. There are two shorter (2.53 Å) and two longer (2.54 Å) La(2)-O(7) bond lengths. There are a spread of La(2)-O(3) bond distances ranging from 2.37-2.79 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(3), one O(5), and four equivalent O(7) atoms to form NiO6 octahedra that share corners with four equivalent Ni(1)O6 octahedra and  a cornercorner with one Tl(1)O5 square pyramid. The corner-sharing octahedral tilt angles are 4°. The Ni(1)-O(3) bond length is 2.21 Å. The Ni(1)-O(5) bond length is 2.26 Å. All Ni(1)-O(7) bond lengths are 1.93 Å. In the second Ni site, Ni(2) is bonded to one O(2), one O(4), and four equivalent O(6) atoms to form NiO6 octahedra that share corners with four equivalent Ni(2)O6 octahedra and  a cornercorner with one Tl(1)O5 square pyramid. The corner-sharing octahedral tilt angles are 4°. The Ni(2)-O(2) bond length is 2.22 Å. The Ni(2)-O(4) bond length is 2.25 Å. All Ni(2)-O(6) bond lengths are 1.93 Å. Tl(1) is bonded to one O(4), one O(5), and three equivalent O(1) atoms to form distorted TlO5 square pyramids that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one Ni(2)O6 octahedra, and corners with six equivalent Tl(1)O5 square pyramids. The corner-sharing octahedral tilt angles are 8°. The Tl(1)-O(4) bond length is 2.12 Å. The Tl(1)-O(5) bond length is 2.12 Å. There is one shorter (2.34 Å) and two longer (2.74 Å) Tl(1)-O(1) bond lengths. There are seven inequivalent O sites. In the first O site, O(4) is bonded to four equivalent Sr(1), one Ni(2), and one Tl(1) atom to form distorted OSr4TlNi octahedra that share  a cornercorner with one O(2)La5Ni octahedra,  a cornercorner with one O(5)Sr4TlNi octahedra, corners with four equivalent O(4)Sr4TlNi octahedra, corners with eight equivalent O(6)Sr2La2Ni2 octahedra,  a cornercorner with one O(1)Sr2Tl3 square pyramid, edges with four equivalent O(4)Sr4TlNi octahedra, edges with three equivalent O(1)Sr2Tl3 square pyramids, and faces with four equivalent O(6)Sr2La2Ni2 octahedra. The corner-sharing octahedral tilt angles range from 2-55°. In the second O site, O(5) is bonded to four equivalent Sr(2), one Ni(1), and one Tl(1) atom to form distorted OSr4TlNi octahedra that share  a cornercorner with one O(3)La5Ni octahedra,  a cornercorner with one O(4)Sr4TlNi octahedra, corners with four equivalent O(5)Sr4TlNi octahedra, corners with eight equivalent O(7)Sr2La2Ni2 octahedra,  a cornercorner with one O(1)Sr2Tl3 square pyramid, edges with four equivalent O(5)Sr4TlNi octahedra, edges with three equivalent O(1)Sr2Tl3 square pyramids, and faces with four equivalent O(7)Sr2La2Ni2 octahedra. The corner-sharing octahedral tilt angles range from 1-54°. In the third O site, O(6) is bonded to two equivalent Sr(1), two equivalent La(1), and two equivalent Ni(2) atoms to form distorted OSr2La2Ni2 octahedra that share corners with two equivalent O(6)Sr2La2Ni2 octahedra, corners with four equivalent O(4)Sr4TlNi octahedra, corners with six equivalent O(2)La5Ni octahedra, corners with two equivalent O(1)Sr2Tl3 square pyramids, edges with two equivalent O(6)Sr2La2Ni2 octahedra, faces with two equivalent O(2)La5Ni octahedra, faces with two equivalent O(4)Sr4TlNi octahedra, and faces with four equivalent O(6)Sr2La2Ni2 octahedra. The corner-sharing octahedral tilt angles range from 4-55°. In the fourth O site, O(7) is bonded to two equivalent Sr(2), two equivalent La(2), and two equivalent Ni(1) atoms to form distorted OSr2La2Ni2 octahedra that share corners with two equivalent O(7)Sr2La2Ni2 octahedra, corners with four equivalent O(5)Sr4TlNi octahedra, corners with six equivalent O(3)La5Ni octahedra, corners with two equivalent O(1)Sr2Tl3 square pyramids, edges with two equivalent O(7)Sr2La2Ni2 octahedra, faces with two equivalent O(3)La5Ni octahedra, faces with two equivalent O(5)Sr4TlNi octahedra, and faces with four equivalent O(7)Sr2La2Ni2 octahedra. The corner-sharing octahedral tilt angles range from 4-54°. In the fifth O site, O(1) is bonded to one Sr(1), one Sr(2), and three equivalent Tl(1) atoms to form distorted OSr2Tl3 square pyramids that share  a cornercorner with one O(4)Sr4TlNi octahedra,  a cornercorner with one O(5)Sr4TlNi octahedra, corners with four equivalent O(6)Sr2La2Ni2 octahedra, corners with four equivalent O(7)Sr2La2Ni2 octahedra, corners with six equivalent O(1)Sr2Tl3 square pyramids, edges with three equivalent O(4)Sr4TlNi octahedra, and edges with three equivalent O(5)Sr4TlNi octahedra. The corner-sharing octahedral tilt angles range from 42-94°. In the sixth O site, O(2) is bonded to five equivalent La(1) and one Ni(2) atom to form distorted OLa5Ni octahedra that share  a cornercorner with one O(4)Sr4TlNi octahedra, corners with four equivalent O(2)La5Ni octahedra, corners with twelve equivalent O(6)Sr2La2Ni2 octahedra, edges with eight equivalent O(2)La5Ni octahedra, and faces with four equivalent O(6)Sr2La2Ni2 octahedra. The corner-sharing octahedral tilt angles range from 2-50°. In the seventh O site, O(3) is bonded to five equivalent La(2) and one Ni(1) atom to form distorted OLa5Ni octahedra that share  a cornercorner with one O(5)Sr4TlNi octahedra, corners with four equivalent O(3)La5Ni octahedra, corners with twelve equivalent O(7)Sr2La2Ni2 octahedra, edges with eight equivalent O(3)La5Ni octahedra, and faces with four equivalent O(7)Sr2La2Ni2 octahedra. The corner-sharing octahedral tilt angles range from 1-50°.