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 Solution77Se,203Tl, and205Tl NMR Spectroscopic and Theoretical Studies of Tl2Ch22-, In2Se22-, and In2Te22-

Abstract

The seleno- and tellurothallate(I) anions Tl2Ch22- (Ch = Se and/or Te) and the 77Se-enriched Tl2Se22- anion have been obtained by extraction of the alloys MTlCh (M = Na, K; Ch = Se, Te), KTlSe0.5Te0.5, and 77Se- 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 Tl2Ch22- anions were characterized in solution by 77Se, 203Tl, and 205Tl NMR spectroscopy, Raman spectroscopy, and X-ray crystallography in (2,2,2-crypt-K+)2Tl2Ch22-. The energy-minimized structures of the Tl2Ch22- (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 In2Ch22- (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 electro...