Synthesis and spectroscopic characterization of eleven mixed-ligand diorganotellurium(IV) compounds containing dithiocarbamate and dithiophosphate ligands

Eleven mixed-ligand organotellurium(IV) compounds of composition R2Te(dtc)(dtp) have been prepared employing two different dithiocarbamate (dtc) and dithiophosphate (dtp) ligands: 1, R2 = C4H8, dtc = S2CNEt2, dtp = S2P(OCH2)2CEt2; 2, R2 = C8H8, dtc = S2CNEt2, dtp = S2P(OCH2)2CEt2; 3, R2 = C4H8O, dtc = S2CNEt2, dtp = S2P(OCH2)2CEt2; 4, R2 = C5H10, dtc = S2CNEt2, dtp = S2P(OCH2)2CEt2; 5, R2 = C4H8, dtc = S2CN(CH2)4, dtp = S2P(OCH2)2CEt2; 6, R2 = C8H8, dtc = S2CN(CH2)4, dtp = S2P(OCH2)2CEt2; 7, R2 = C4H8O, dtc = S2CN(CH2)4, dtp = S2P(OCH2)2CEt2; 8, R2 = C5H10, dtc = S2CN(CH2)4, dtp = S2P(OCH2)2CEt2; 9, R2 = C4H8, dtc = S2CN(CH2)4, dtp = S2P(OCH2)2CMenPr; 10, R2 = C8H8, dtc = S2CN(CH2)4, dtp = S2P(OCH2)2CMenPr; 11, R2 = C4H8O, dtc = S2CN(CH2)4, dtp = S2P(OCH2)2CMenPr. 1–11 were characterized by mass spectrometry, IR spectroscopy and multinuclear NMR (1H, 13C, 31P, 125Te) spectroscopy. The molecular structures of 2, 4 and 6, of which 2 crystallized in form of two different polymorphs (2a and 2b), were analyzed by single-crystal X-ray diffraction analysis. This analysis showed that the coordination mode of both ligand types is anisobidentate. When considering only covalent Te–C and Te–S bonds, the coordination geometry of the tellurium atoms is distorted Ψ-trigonal-bipyramidal, since the lone pair is stereochemically active and occupies an equatorial position together with the carbon atoms of the tellurocycles. If secondary Te⋯S interactions are considered also, the coordination sphere around tellurium is best described as bicapped Ψ-trigonal-bipyramidal for the complexes with two intramolecular Te⋯S secondary bonds and monomeric molecular structures, and pentagonal-bipyramidal for the complexes in which neighboring molecules in the crystal lattice are linked through additional weak intermolecular Te⋯S secondary bonds to form dimeric supramolecular aggregates.