Ta11(SiSe4)2 crystallizes in the orthorhombic Pnnm space group. There are six inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 5-coordinate geometry to two equivalent Si(1), one Se(1), and two equivalent Se(3) atoms. In the second Ta site, Ta(2) is bonded in a 5-coordinate geometry to two equivalent Si(1), one Se(2), and two equivalent Se(3) atoms. In the third Ta site, Ta(3) is bonded in a 5-coordinate geometry to one Si(1), two equivalent Se(1), and two equivalent Se(4) atoms. In the fourth Ta site, Ta(4) is bonded in a distorted square co-planar geometry to two equivalent Si(1) and two equivalent Se(3) atoms. In the fifth Ta site, Ta(5) is bonded in a 5-coordinate geometry to two equivalent Si(1), one Se(4), and two equivalent Se(1) atoms. In the sixth Ta site, Ta(6) is bonded in a 5-coordinate geometry to one Si(1), one Se(1), one Se(4), and two equivalent Se(2) atoms. Si(1) is bonded in a 9-coordinate geometry to one Ta(3), one Ta(4), one Ta(6), two equivalent Ta(1), two equivalent Ta(2), and two equivalent Ta(5) atoms. There are four inequivalent Se sites. In the first Se site, Se(3) is bonded in a 5-coordinate geometry to one Ta(4), two equivalent Ta(1), and two equivalent Ta(2) atoms. In the second Se site, Se(4) is bonded in a 4-coordinate geometry to one Ta(5), one Ta(6), and two equivalent Ta(3) atoms. In the third Se site, Se(1) is bonded in a 6-coordinate geometry to one Ta(1), one Ta(6), two equivalent Ta(3), and two equivalent Ta(5) atoms. In the fourth Se site, Se(2) is bonded in a distorted T-shaped geometry to one Ta(2) and two equivalent Ta(6) atoms.
Ta11(SiSe4)2 crystallizes in the orthorhombic Pnnm space group. There are six inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 5-coordinate geometry to two equivalent Si(1), one Se(1), and two equivalent Se(3) atoms. Both Ta(1)-Si(1) bond lengths are 2.56 Å. The Ta(1)-Se(1) bond length is 2.67 Å. Both Ta(1)-Se(3) bond lengths are 2.71 Å. In the second Ta site, Ta(2) is bonded in a 5-coordinate geometry to two equivalent Si(1), one Se(2), and two equivalent Se(3) atoms. Both Ta(2)-Si(1) bond lengths are 2.56 Å. The Ta(2)-Se(2) bond length is 2.54 Å. Both Ta(2)-Se(3) bond lengths are 2.71 Å. In the third Ta site, Ta(3) is bonded in a 5-coordinate geometry to one Si(1), two equivalent Se(1), and two equivalent Se(4) atoms. The Ta(3)-Si(1) bond length is 2.77 Å. Both Ta(3)-Se(1) bond lengths are 2.69 Å. Both Ta(3)-Se(4) bond lengths are 2.62 Å. In the fourth Ta site, Ta(4) is bonded in a distorted square co-planar geometry to two equivalent Si(1) and two equivalent Se(3) atoms. Both Ta(4)-Si(1) bond lengths are 2.72 Å. Both Ta(4)-Se(3) bond lengths are 2.77 Å. In the fifth Ta site, Ta(5) is bonded in a 5-coordinate geometry to two equivalent Si(1), one Se(4), and two equivalent Se(1) atoms. Both Ta(5)-Si(1) bond lengths are 2.54 Å. The Ta(5)-Se(4) bond length is 2.64 Å. Both Ta(5)-Se(1) bond lengths are 2.71 Å. In the sixth Ta site, Ta(6) is bonded in a 5-coordinate geometry to one Si(1), one Se(1), one Se(4), and two equivalent Se(2) atoms. The Ta(6)-Si(1) bond length is 2.74 Å. The Ta(6)-Se(1) bond length is 2.81 Å. The Ta(6)-Se(4) bond length is 2.66 Å. Both Ta(6)-Se(2) bond lengths are 2.61 Å. Si(1) is bonded in a 9-coordinate geometry to one Ta(3), one Ta(4), one Ta(6), two equivalent Ta(1), two equivalent Ta(2), and two equivalent Ta(5) atoms. There are four inequivalent Se sites. In the first Se site, Se(3) is bonded in a 5-coordinate geometry to one Ta(4), two equivalent Ta(1), and two equivalent Ta(2) atoms. In the second Se site, Se(4) is bonded in a 4-coordinate geometry to one Ta(5), one Ta(6), and two equivalent Ta(3) atoms. In the third Se site, Se(1) is bonded in a 6-coordinate geometry to one Ta(1), one Ta(6), two equivalent Ta(3), and two equivalent Ta(5) atoms. In the fourth Se site, Se(2) is bonded in a distorted T-shaped geometry to one Ta(2) and two equivalent Ta(6) atoms.