Oxidation behavior of intramolecularly coordinated unsymmetrical diorganotellurides: isolation of novel tetraorganoditelluronic acids, [RR′Te(μ-O)(OH)2]2

Abstract

The oxidation reaction of unsymmetrical diorganotellurides, namely, bis[2-{(dimethylamino)methyl}aryl]tellurides [aryl = phenyl (6), 2-methylphenyl (7), 2,6-dimethylphenyl (8) and 2,6-diisopropylphenyl (9)] with meta-chloroperbenzoic acid afforded the first examples of tetraorganoditelluronic acids, [RR′Te(μ-O)(OH)₂]₂, where R = 2-NMe₂CH₂C₆H₄, R′ = C₆H₅ (10), 2-MeC₆H₄ (11), 2,6-MeC₆H₃ (12) and 2,6-ⁱPrC₆H₃ (13). The structures of tetraorganoditelluronic acids 10–13 were authenticated by single crystal X-ray diffraction studies. From the molecular structures of 10–13, it was observed that the sp³ N-donor atoms, which were initially involved in intramolecular Te⋯N bonding interactions in diorganotellurides 6–9, did not interact with the tellurium atoms in tetraorganoditelluronic acids 10–13. The ¹²⁵Te chemical shifts for 10–13 were considerably downfield shifted as compared with the values observed for the corresponding tellurides 6–9. The relative stabilities of the tetraorganoditelluronic acids 10–13 with respect to their lighter analogues (S and Se) have been assessed using DFT calculations.