Solvothermal Synthesis and Crystal Structure of Te8[U2Br10], Containing a Polymeric Chalcogen Cation (Te82+)n

Abstract

Under solvothermal conditions, the reaction of Te, TeBr 4 and UBr 5 in SiBr 4 at 200°C yields Te 8 [U 2 Br 10 ] as silvery crystals. The crystal structure (triclinic, P1, a ϭ 900.8(4), b ϭ 1205.1(5), c ϭ 1366.0(6) pm, α ϭ 80.93(4)°, β ϭ 76.83(3)°, γ ϭ 78.84(3)°, Z ϭ 2) is built of one-dimensional polymeric (Te 8 2ϩ ) n cations consisting of boat-shaped Te 6 rings, which are linked by Te 2 bridges. The anions [U 2 Br 10 2Ϫ

[Te8]2[Ta4O4Cl16]: A Two‐dimensional Tellurium Polycation obtained via Ionic Liquid‐Based Synthesis

“…Moreover, joined bicyclic polycations such as in Te 8 [WCl 6 ] 2 are known 11. Finally, infinite chain‐like catena ‐octatellurium(2+) cations have been described for Te 8 [Bi 4 Cl 14 ]13 and Te 8 [U 2 Br 10 ] 14. Although [Te 8 ] 2+ herein is related, the situation in [Te 8 ] 2 [Ta 4 O 4 Cl 16 ] is nevertheless significantly different since the [Te–Te–(Te 6 )] n 2+ chains in the title compound show a much stronger folding (Figure 3).…”

“… The infinite [Te–Te–(Te 6 )] n 2+ chain in [Te 8 ] 2 [Ta 4 O 4 Cl 16 ] as compared to [Te 8 ][U 2 Br 10 ]14 and [Te 8 ][Bi 4 Cl 14 ] 13…”

“…Thus, the upper edge of the band gap is visible at 850 nm (1.45 eV) in UV/Vis spectra. By extrapolation the band gap can be estimated to 1050–1100 nm or 1.1–1.2 eV, which represents a typical value of infinite polycationic tellurium species 11–14…”

“…Most often polytellurium cations are obtained as separated cations and with [Te 4 ] 2+ , [Te 6 ] 2+ and [Te 8 ] 2+ as the most prominent examples 7–11. Infinite polytelluriumcations are comparably rare and have been yet identified in Te 8 [WCl 6 ] 2 , [Te 15 X 4 ] n [ M O X 4 ] 2 n ( X : Cl, Br; M: Mo, W),Te 8 [Bi 4 Cl 14 ] and Te 8 [U 2 Br 10 ] 11–14…”

[Te8][NbOCl4]2containing an infinite chain-like {[Te–Te–Te–(Te5)]2+}npolycation

“…Tellurium is well known for its chain-like structural arrangement. Such infinite chains are characteristic of the structure of the element (Straumanis, 1940) and are also found in compounds containing polycationic tellurium species such as Te 8 [Bi 4 Cl 14 ] (Beck & Stankowski, 2001), Te 8 [U 2 Br 10 ] (Beck & Fischer, 2002) (Beck & Baumann, 2004).…”