DOE OSTI2020
Ta20Pd9S50 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are six inequivalent Ta+4.10+ sites. In the first Ta+4.10+ site, Ta+4.10+ is bonded to seven S2- atoms to form distorted TaS7 pentagonal bipyramids that share edges with two equivalent TaS7 pentagonal bipyramids, edges with two equivalent TaS6 pentagonal pyramids, and faces with two equivalent TaS7 pentagonal bipyramids. There are a spread of Ta–S bond distances ranging from 2.48–2.68 Å. In the second Ta+4.10+ site, Ta+4.10+ is bonded to seven S2- atoms to form distorted TaS7 pentagonal bipyramids that share edges with two TaS7 pentagonal bipyramids, edges with two TaS6 pentagonal pyramids, and faces with two TaS7 pentagonal bipyramids. There are a spread of Ta–S bond distances ranging from 2.48–2.73 Å. In the third Ta+4.10+ site, Ta+4.10+ is bonded to seven S2- atoms to form distorted TaS7 pentagonal bipyramids that share edges with two TaS7 pentagonal bipyramids, edges with two TaS6 pentagonal pyramids, and faces with two TaS7 pentagonal bipyramids. There are a spread of Ta–S bond distances ranging from 2.48–2.69 Å. In the fourth Ta+4.10+ site, Ta+4.10+ is bonded to six S2- atoms to form distorted TaS6 pentagonal pyramids that share edges with two TaS7 pentagonal bipyramids and edges with two TaS6 pentagonal pyramids. There are a spread of Ta–S bond distances ranging from 2.46–2.48 Å. In the fifth Ta+4.10+ site, Ta+4.10+ is bonded to six S2- atoms to form distorted TaS6 pentagonal pyramids that share edges with two TaS7 pentagonal bipyramids and edges with two TaS6 pentagonal pyramids. There are a spread of Ta–S bond distances ranging from 2.46–2.48 Å. In the sixth Ta+4.10+ site, Ta+4.10+ is bonded to six S2- atoms to form distorted TaS6 pentagonal pyramids that share edges with two equivalent TaS7 pentagonal bipyramids and edges with two equivalent TaS6 pentagonal pyramids. There are a spread of Ta–S bond distances ranging from 2.46–2.48 Å. There are five inequivalent Pd2+ sites. In the first Pd2+ site, Pd2+ is bonded in a square co-planar geometry to four S2- atoms. There are two shorter (2.35 Å) and two longer (2.36 Å) Pd–S bond lengths. In the second Pd2+ site, Pd2+ is bonded in a square co-planar geometry to four S2- atoms. There are two shorter (2.35 Å) and two longer (2.36 Å) Pd–S bond lengths. In the third Pd2+ site, Pd2+ is bonded in a square co-planar geometry to four S2- atoms. There are two shorter (2.35 Å) and two longer (2.36 Å) Pd–S bond lengths. In the fourth Pd2+ site, Pd2+ is bonded in a distorted square co-planar geometry to four S2- atoms. There are two shorter (2.50 Å) and two longer (2.51 Å) Pd–S bond lengths. In the fifth Pd2+ site, Pd2+ is bonded in a distorted rectangular see-saw-like geometry to four S2- atoms. There are two shorter (2.47 Å) and two longer (2.49 Å) Pd–S bond lengths. There are fifteen inequivalent S2- sites. In the first S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+4.10+ atoms. In the second S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+4.10+ atoms. In the third S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+4.10+ atoms. In the fourth S2- site, S2- is bonded in a 4-coordinate geometry to three Ta+4.10+ and one Pd2+ atom. In the fifth S2- site, S2- is bonded in a 5-coordinate geometry to three Ta+4.10+ and two Pd2+ atoms. In the sixth S2- site, S2- is bonded in a 5-coordinate geometry to three Ta+4.10+ and two equivalent Pd2+ atoms. In the seventh S2- site, S2- is bonded in a 3-coordinate geometry to two Ta+4.10+ and one Pd2+ atom. In the eighth S2- site, S2- is bonded in a 3-coordinate geometry to two Ta+4.10+ and one Pd2+ atom. In the ninth S2- site, S2- is bonded in a 3-coordinate geometry to two equivalent Ta+4.10+ and one Pd2+ atom. In the tenth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+4.10+ atoms. In the eleventh S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+4.10+ atoms. In the twelfth S2- site, S2- is bonded in a 3-coordinate geometry to three Ta+4.10+ atoms. In the thirteenth S2- site, S2- is bonded in a 3-coordinate geometry to two Ta+4.10+ and one Pd2+ atom. In the fourteenth S2- site, S2- is bonded in a 3-coordinate geometry to two Ta+4.10+ and one Pd2+ atom. In the fifteenth S2- site, S2- is bonded in a 3-coordinate geometry to two equivalent Ta+4.10+ and one Pd2+ atom.