First Examples of Thallium Chalcogenide Cages. Syntheses, 77Se, 203Tl, and 205Tl NMR Study of the Tl4Se5 4- and Tl4Se6 4- Anions, the X-ray Crystal Structure of (2,2,2-crypt-K+)3Tl5Se5 3-, and Theoretical Studies †

The Tl5Se5(3-) anion has been obtained by extracting KTlSe in ethylenediamine in the presence of 2,2,2-crypt. The salt, (2,2,2-crypt-K+)3Tl5Se5(3-), crystallizes in the triclinic system, space group P1, with Z = 2 and a = 11.676(2) A, b = 16.017(3) A, c = 25.421(5) A, alpha = 82.42(3) degrees, beta = 88.47(3) degrees, gamma = 69.03(3) degrees at -123 degrees C. Two other mixed oxidation state TlI/TlIII anions; Tl4Se5(4-) and Tl4Se6(4-), have …