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Preparation, Crystal Structure, Physical Properties, and Electronic Band Structure of TlTaS3Professor Welf Bronger zum 70. Geburtstag gewidmet

“…The shortest distance d Ta-S(2) of about 2.2 Å is very similar to those found in the complex anions Ta 2 S 11 4Ϫ in Tl 4 Ta 2 S 11 [1] and t-K 4 Ta 2 S 11 [25]. Hence, it may also correspond to a Ta -S "double" bond as discussed for K 4 Ta 2 S 11 .…”

“…Hence, it may also correspond to a Ta -S "double" bond as discussed for K 4 Ta 2 S 11 . The MIR spectrum shows a strong mode located at 429 cm Ϫ1 due to the Ta-S stretching vibration (Tl 4 Ta 2 S 11 429 cm Ϫ1 [1] and t-K 4 Ta 2 S 11 431 cm Ϫ1 [25]). The optical band gap was estimated from the evaluation of the diffuse UV/Vis-reflectance spectra yielding E g ഠ 0.78 eV.…”

Synthesis, crystal structure and properties of K2Ta2S10: A novel ternary tantalum polysulfide with TaS8 polyhedra forming infinite anionic chains

“…The Ta-S distances range from 2.463(1) to 2.639(1) Å with an average /Ta-SS of 2.527(1) Å for Ta(1) and from 2.455(1) to 2.654(1) Å (average /Ta-SS: 2.526(1) Å ) for Ta(2) ( Table 3). These distances are in good agreement with the values reported for other potassium tantalum sulfides [13,14,16] and the sum of ionic radii of Ta and S as well [27].…”

“…In addition, all these low intense Ta-S vibrational modes form combinations with n 1 , but no subsidiary progressions with other possible Raman active Ta-S modes is observed. The bathochromic shift of the Ta [14] as well as in TlTaS 3 [29].…”

“…Depending on the reaction conditions and size of the cations, structures with discrete molecular anions [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] or chains [21][22][23][24] are formed. In the case of tantalum, examples include discrete tetrahedral TaQ 4 units like in A 3 TaQ 4 (A ¼ K, Rb, Cs, Q ¼ S, Se) [6][7][8], Ta 2 S 11 groups like in A 4 Ta 2 S 11 (A ¼ K, Rb, Cs) [13][14][15], complex Ta 4 S 22 units like in A 6 Ta 4 S 22 (A ¼ K, Rb, Cs) [16,18,19], and Ta 4 S 25 like in Rb 6 Ta 4 S 25 units [20]. The Ta 2 S 11 unit is composed of two face sharing TaS 7 pentagonal bipyramids and is a building block which may be interconnected through S 2 2À and S 5 2À polyanions yielding the Ta 4 S 22 and Ta 4 S 25 unit.…”