Tl2[B10H10] und Tl2[B12H12]: Kristallstrukturen, Raman-Spektren und Tl+-Lone-Pair-Lumineszenz im Vergleich

Abstract

Abstract Thallium(I) decahydro-closo-decaborate Tl2[B10H10] and thallium(I) dodecahydro-closo-dodecaborate Tl2[B12H12] are readily available as microcrystalline powders from reactions of thallium(I) carbonate Tl2[CO3] with aqueous solutions of the respective free acid (H3O)2[B10H10] or (H3O)2[B12H12]. Tl2[B12H12] crystallizes with an anti-fluorite related structure (cubic, F m 3 ‾ $Fm\bar{3}$ , a = 1074.23(8) pm, Z = 4). Each Tl+ cation is coordinated by four icosahedral [B12H12]2– anions (d(B–B) = 180–181 pm) providing a twelvefold coordination sphere of hydrogen atoms (d(Tl–H) = 296 pm). Tl2[B10H10] crystallizes monoclinically in the space group P21/n with a = 704.03(5), b = 1111.45(8), c = 1281.16(9) pm and β = 94.912(3)° for Z = 4. The bicapped square antiprismatic [B10H10]2– anions (d(B–B) = 147–176 pm to the two apical boron atoms, d(B–B) = 161–199 pm within the corpus) again form distorted tetrahedra around the (Tl1)+, but square pyramids around the (Tl2)+ cations. Thus (Tl1)+ is coordinated by 12 hydrogen atoms (d(Tl1–H) = 275–315 pm), but (Tl2)+ only by 11 of them (d(Tl2–H) = 267–357 pm). Both compounds show a greenish-yellow photoluminescence caused by an interconfigurational 6sp –6s 2 emission (3Pn→1S0, n = 0–2) at the Tl+ cation.