Synthesis, spectroscopic and structural studies of O-methyl and O-isopropyl monothiocarbonate (monoxanthate) derivatives of dimethyl-and diphenyltellurium(IV). Crystal structures of Me2Te[SCO2(i-Pr)]2, Ph2Te[SCO2(i-Pr)]2, Me2TeCl[SCO2Me], and Me2TeBr[SCO2(i-Pr)]

Abstract

Monothiocarbonate derivatives of diorganotellurium(IV), R2Te[SCO2R′]2, and R2TeX[SCO2R′], where R = Me, Ph; R′ = Me, i-Pr; X = Cl, Br, and I, have been prepared and characterized by vibrational and 1H, 13C, and 125Te NMR spectroscopy. Me2Te[SCO2(i-Pr)]2 (2): P21/n (No. 14) with cell parameters a = 6.942(6) Å, b = 25.599(3) Å, c = 9.404(6) Å, β = 94.48(6)°, V = 1666(1) Å3, Z = 4, R = 0.0648, Rw = 0.0624; Ph2Te[SCO2(i-Pr)]2 (4): P21/n (No. 14) with a = 12.360(4) Å, b = 12.277(3) Å, c = 15.066(3) Å, β = 102.82(2)°, V = 2229.1(9) Å3, Z = 4, R = 0.0368, Rw = 0.0312; Me2TeCl[SCO2Me] (5); P21/c (No. 14) with a = 5.193(2) Å, b = 18.118(4) Å, c = 9.613(5) Å, β = 91.31(6)°, V = 904.2(6) Å3, Z = 4, R = 0.0396, Rw = 0.0361; and Me2TeBr[SCO2(i-Pr)] (8): P21/n (No. 14) with a = 11.701(2) Å, b = 6.250(2) Å, c = 16.152(2) Å, β = 98.43(1)°, V = 1168.4(4) Å3, Z = 4, R = 0.0369, Rw = 0.0325. In all molecules, the immediate environment about tellurium is that of the saw-horse structure in which the lone pair is assumed to be stereochemically active and occupying an equatorial position in a distorted trigonal bipyramid. In 2 and 5, the terminal oxygen atoms are oriented toward tellurium, whereas in 4, one O(i-Pr) group is oriented toward tellurium, as it is in 8. In the latter cases, the terminal oxygen atoms act as weak bridges to form a pseudo dimeric species in 4 and a pseudo polymer in 8. Supramolecular interactions in 2 and 5 lead to a sulfur-bridged dimer in the former and a chlorine-bridged polymer in the latter. Key words: structure, tellurium, dimethyl, diphenyl, monothiocarbonates.