Nb3Tl2Br9 crystallizes in the monoclinic C2/m space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one Br(6), two equivalent Br(3), and two equivalent Br(5) atoms to form distorted corner-sharing NbBr5 square pyramids. In the second Nb site, Nb(2) is bonded to one Br(1), one Br(2), one Br(3), one Br(4), and one Br(5) atom to form distorted corner-sharing NbBr5 square pyramids. Tl(1) is bonded in a 3-coordinate geometry to one Br(6) and two equivalent Br(4) atoms. There are six inequivalent Br sites. In the first Br site, Br(5) is bonded in a 2-coordinate geometry to one Nb(1) and one Nb(2) atom. In the second Br site, Br(6) is bonded in a trigonal planar geometry to one Nb(1) and two equivalent Tl(1) atoms. In the third Br site, Br(1) is bonded in a 2-coordinate geometry to two equivalent Nb(2) atoms. In the fourth Br site, Br(2) is bonded in a 2-coordinate geometry to two equivalent Nb(2) atoms. In the fifth Br site, Br(3) is bonded in a 2-coordinate geometry to one Nb(1) and one Nb(2) atom. In the sixth Br site, Br(4) is bonded in a 3-coordinate geometry to one Nb(2) and two equivalent Tl(1) atoms.
Nb3Tl2Br9 crystallizes in the monoclinic C2/m space group. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one Br(6), two equivalent Br(3), and two equivalent Br(5) atoms to form distorted corner-sharing NbBr5 square pyramids. The Nb(1)-Br(6) bond length is 2.83 Å. Both Nb(1)-Br(3) bond lengths are 2.62 Å. Both Nb(1)-Br(5) bond lengths are 2.62 Å. In the second Nb site, Nb(2) is bonded to one Br(1), one Br(2), one Br(3), one Br(4), and one Br(5) atom to form distorted corner-sharing NbBr5 square pyramids. The Nb(2)-Br(1) bond length is 2.64 Å. The Nb(2)-Br(2) bond length is 2.62 Å. The Nb(2)-Br(3) bond length is 2.61 Å. The Nb(2)-Br(4) bond length is 2.87 Å. The Nb(2)-Br(5) bond length is 2.62 Å. Tl(1) is bonded in a 3-coordinate geometry to one Br(6) and two equivalent Br(4) atoms. The Tl(1)-Br(6) bond length is 3.22 Å. There is one shorter (3.21 Å) and one longer (3.24 Å) Tl(1)-Br(4) bond length. There are six inequivalent Br sites. In the first Br site, Br(5) is bonded in a 2-coordinate geometry to one Nb(1) and one Nb(2) atom. In the second Br site, Br(6) is bonded in a trigonal planar geometry to one Nb(1) and two equivalent Tl(1) atoms. In the third Br site, Br(1) is bonded in a 2-coordinate geometry to two equivalent Nb(2) atoms. In the fourth Br site, Br(2) is bonded in a 2-coordinate geometry to two equivalent Nb(2) atoms. In the fifth Br site, Br(3) is bonded in a 2-coordinate geometry to one Nb(1) and one Nb(2) atom. In the sixth Br site, Br(4) is bonded in a 3-coordinate geometry to one Nb(2) and two equivalent Tl(1) atoms.