Materials Data on K7(Si2Te5)4 by Materials Project
K7(Si2Te5)4 crystallizes in the monoclinic Pc space group. The structure is three-dimensional. there are seven inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 5-coordinate geometry to six Te+1.95- atoms. There are a spread of K–Te bond distances ranging from 3.55–4.26 Å. In the second K1+ site, K1+ is bonded in a 7-coordinate geometry to seven Te+1.95- atoms. There are a spread of K–Te bond distances ranging from 3.55–4.14 Å. In the third K1+ site, K1+ is bonded in a 8-coordinate geometry to eight Te+1.95- atoms. There are a spread of K–Te bond distances ranging from 3.48–4.14 Å. In the fourth K1+ site, K1+ is bonded in a 6-coordinate geometry to six Te+1.95- atoms. There are a spread of K–Te bond distances ranging from 3.61–3.83 Å. In the fifth K1+ site, K1+ is bonded in a distorted rectangular see-saw-like geometry to four Te+1.95- atoms. There are a spread of K–Te bond distances ranging from 3.39–3.64 Å. In the sixth K1+ site, K1+ is bonded in a 8-coordinate geometry to eight Te+1.95- atoms. There are a spread of K–Te bond distances ranging from 3.53–4.19 Å. In the seventh K1+ site, K1+ is bonded in a 7-coordinate geometry to seven Te+1.95- atoms. There are a spread of K–Te bond distances ranging from 3.54–4.01 Å. There are eight inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded in a trigonal pyramidal geometry to four Te+1.95- atoms. There are a spread of Si–Te bond distances ranging from 2.56–2.59 Å. In the second Si4+ site, Si4+ is bonded in a water-like geometry to two Te+1.95- atoms. There are one shorter (2.49 Å) and one longer (2.59 Å) Si–Te bond lengths. In the third Si4+ site, Si4+ is bonded in a trigonal non-coplanar geometry to three Te+1.95- atoms. There are a spread of Si–Te bond distances ranging from 2.61–2.65 Å. In the fourth Si4+ site, Si4+ is bonded in a trigonal planar geometry to three Te+1.95- atoms. There are a spread of Si–Te bond distances ranging from 2.48–2.62 Å. In the fifth Si4+ site, Si4+ is bonded in a trigonal non-coplanar geometry to three Te+1.95- atoms. There are a spread of Si–Te bond distances ranging from 2.50–2.66 Å. In the sixth Si4+ site, Si4+ is bonded in a trigonal non-coplanar geometry to three Te+1.95- atoms. There are a spread of Si–Te bond distances ranging from 2.56–2.64 Å. In the seventh Si4+ site, Si4+ is bonded in a single-bond geometry to one Te+1.95- atom. The Si–Te bond length is 2.58 Å. In the eighth Si4+ site, Si4+ is bonded in a distorted T-shaped geometry to three Te+1.95- atoms. There are a spread of Si–Te bond distances ranging from 2.55–2.75 Å. There are twenty inequivalent Te+1.95- sites. In the first Te+1.95- site, Te+1.95- is bonded in a 5-coordinate geometry to three K1+, one Si4+, and one Te+1.95- atom. The Te–Te bond length is 2.82 Å. In the second Te+1.95- site, Te+1.95- is bonded in a distorted rectangular see-saw-like geometry to three K1+ and one Si4+ atom. In the third Te+1.95- site, Te+1.95- is bonded in a 2-coordinate geometry to one K1+ and four Te+1.95- atoms. There are a spread of Te–Te bond distances ranging from 2.79–3.70 Å. In the fourth Te+1.95- site, Te+1.95- is bonded in a 3-coordinate geometry to one K1+, one Si4+, and one Te+1.95- atom. In the fifth Te+1.95- site, Te+1.95- is bonded in a 4-coordinate geometry to two K1+, two Si4+, and one Te+1.95- atom. In the sixth Te+1.95- site, Te+1.95- is bonded in a 2-coordinate geometry to two K1+, two Si4+, and one Te+1.95- atom. In the seventh Te+1.95- site, Te+1.95- is bonded in a 1-coordinate geometry to two K1+, one Si4+, and one Te+1.95- atom. In the eighth Te+1.95- site, Te+1.95- is bonded in a 2-coordinate geometry to one K1+, two Si4+, and one Te+1.95- atom. The Te–Te bond length is 2.94 Å. In the ninth Te+1.95- site, Te+1.95- is bonded in a 3-coordinate geometry to two K1+, two Si4+, and one Te+1.95- atom. The Te–Te bond length is 3.00 Å. In the tenth Te+1.95- site, Te+1.95- is bonded in a 4-coordinate geometry to three K1+ and one Si4+ atom. In the eleventh Te+1.95- site, Te+1.95- is bonded in a 2-coordinate geometry to three K1+ and one Te+1.95- atom. The Te–Te bond length is 2.80 Å. In the twelfth Te+1.95- site, Te+1.95- is bonded in a 2-coordinate geometry to one K1+ and one Si4+ atom. In the thirteenth Te+1.95- site, Te+1.95- is bonded in a distorted trigonal non-coplanar geometry to one K1+ and two Si4+ atoms. In the fourteenth Te+1.95- site, Te+1.95- is bonded in a 7-coordinate geometry to three K1+ and four Te+1.95- atoms. There are one shorter (3.03 Å) and one longer (3.13 Å) Te–Te bond lengths. In the fifteenth Te+1.95- site, Te+1.95- is bonded in a 1-coordinate geometry to three K1+, one Si4+, and two Te+1.95- atoms. The Te–Te bond length is 3.50 Å. In the sixteenth Te+1.95- site, Te+1.95- is bonded in a 4-coordinate geometry to three K1+, one Si4+, and one Te+1.95- atom. In the seventeenth Te+1.95- site, Te+1.95- is bonded in a 4-coordinate geometry to three K1+ and one Si4+ atom. In the eighteenth Te+1.95- site, Te+1.95- is bonded in a distorted single-bond geometry to two K1+ and one Si4+ atom. In the nineteenth Te+1.95- site, Te+1.95- is bonded in a 6-coordinate geometry to four K1+, one Si4+, and one Te+1.95- atom. In the twentieth Te+1.95- site, Te+1.95- is bonded in a 6-coordinate geometry to three K1+, one Si4+, and two Te+1.95- atoms.