CRYSTAL-STRUCTURES OF POTASSIUM CRYPTATED SALTS OF THE TESE2(2-), PYRAMIDAL TESE3(2-), AND MIXED COMPOUNDS CONTAINING PYRAMIDAL TESE3(2-) AND CHAIN TEXSE4-X(2-) ANIONS AND SE-77 AND TE-125 SOLUTION NMR-STUDIES OF THE PYRAMIDAL SELENOTHIOTELLURITE ANIONS TESMSE3-M(2-) (M = 0-3)

The preparation of several compounds containing mixed tellurium-selenium and tellurium-sulfur-selenium anions as cryptated potassium salts [crypt = 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane] are reported along with the X-ray crystal structures of four compounds (1-4) containing Te-Se dianions. Compound 1 (2,2,2-crypt-K+)2TeSe22-.en, crystallizes in the triclinic space group P1 with a = 10.9725 (8) angstrom, b = 12.1940 (9) angstrom, c = 12.3242 (10) angstrom, alpha = 59.182 (7)-degrees, beta = 73.781 (7)-degrees, gamma = 67.718 (6)-degrees, V = 1303 angstrom 3, D(x) = 1.500 g cm-3 for Z = 1, and R (R(w)) = 0.0382 (0.0465) for 4459 observed [I greater-than-or-equal-to 3-sigma(I)] data. Similarly, compound 2, (2,2,2-crypt-K+)2TeSe32-.en, crystallizes in the trigonal space group P3(2) (No. 145) with a = 12.386 (5) angstrom, c = 30.669 (15) angstrom, V = 4076 angstrom 3, D(x) = 1.537 g cm-3 for Z = 3, and R (R(w)) = 0.0574 (0.0638) for 1810 observed [I greater-than-or-equal-to 2.5-sigma(I)] data. However, compounds 3 and 4 were found to be mixed crystals containing principally the pyramidal TeSe32- anion as well as different minor amounts of a chain tetrachalcogen anion, although the overall Te/Se composition of the averaged anion in each compound is essentially constant for the two compounds at Te0.9Se3.42-. Compound 3 [values for 4 in brackets] crystallizes in the monoclinic space group P2(1)/n (No. 14) with a = 12.252 (4) angstrom [12.286 (2) angstrom], b = 21.643 (3) angstrom [21.587 (9) angstrom], c = 20.718 (3) angstrom [20.759 (2) angstrom], beta = 97.45 (2)-degrees [97.61 (1)-degrees], V = 5447 angstrom 3 [5457 angstrom 3], and R (R(w)) = 0.0733 (0.0730) [0.0667 (0.0632)] for 2150 [2898] observed reflections. In 1, the Te-Se bond lengths and Se-Te-Se bond angle in the TeSe22- anion are 2.501 (1) and 2.504 (1) angstrom and 111.3 (1)-degrees, respectively, while in 2 the Te-Se bond lengths in the pyramidal TeSe32- anion are 2.454 (4), 2.460 (4), and 2.465 (4) angstrom and the Se-Te-Se bond angles are 104.8 (2), 107.4 (1), and 108.9 (1)-degrees. In compound 3, the anion site consists of ca. 89% of a pyramidal anion (assumed to be TeSe32-) and 11% of an open-chain tetrachalcogen anion with all compositions except TeSe32- being predicted on the basis of NMR data (see preceding paper), while in 4 the pyramidal:chain dianion ratio is ca. 81:19. In addition, the pyramidal-shaped selenothiotellurite anions TeSmSe3-m2- (m = 0-3) have been prepared and characterized in ethylenediamine (en) solutions. Trends in the Se-77 and Te-125 chemical shifts and in the one-bond spin-spin coupling constants, 1J(Te-125 - Se-77), for the latter species are reported and discussed in terms of the relative electronegativities of sulfur and selenium.