Tl2Ch22- (Ch = Se and/or Te) anions:: X-ray crystal structures and Raman spectra of (2,2,2-crypt-K+)2Tl2Se22- and (2,2,2-crypt-K+)2Tl2Te22- and solution 77Se, 203Tl, and 205Tl NMR spectroscopic and theoretical studies of Tl2Ch22-, In2Se22-, and In2Te22-

The seleno-and tellurothallate(I) anions Tl(2)Ch(2)(2-)(Ch = Se and/or Te) and the Se-77-enriched Tl2Se22- anion have been obtained by extraction of the alloys MTlCh (M = Na, K; Ch = Se, Te), KTlSe0.5Te0.5, and Se-77-enriched KTlSe in ethylenediamine and liquid NH3 and in the presence of a stoichiometric excess of 2,2,2-crypt with respect to M+. The butterfly-shaped Tl(2)Ch(2)(2-)anions were characterized in solution by Se-77, Tl-203 and Tl-305 NMR spectroscopy, Raman spectroscopy, and X-ray crystallography in (2,2.2-crypt K+)(2)Tl(2)Ch(2)(2-); The energy minimized structures of the Tl(2)Ch(2)(2-)(Ch = Se and/or Te) anions were calculated by using density functional theory calculations confirming the nonplanar geometries of all three anions, which are compared with those of the presently unknown In(2)Ch(2-) (Ch = Se, Te) anions. The magnitudes of the relativistically corrected reduced coupling constants, (KTl-Ch)(RC) are consistent with essentially pure p-bonded rings whereas the magnitudes of (KTl-Tl)(RC) suggest significant s electron density along the Tl ... Tl axes and is confirmed by theory. Density functional theory calculations were also used to assign the solid-state vibrational spectra of Tl2Se22- and Tl2Te2-. The variation of the Tl-205-Tl-203 spin-spin coupling constants with solvent and temperature, the differences between the calculated and experimentally determined fold angles, and the low experimental and calculated vibrational frequencies of the anion deformation modes indicate that the anion geometries are significantly influenced by environmental factors.