Synthesis and Properties of Tellurinic Anhydride–Tellurone Adducts

The synthesis and characterization
of stable tellurinic anhydride–tellurone
adducts are reported. Treatment of aryltellurinic anhydride with diaryl
tellurone gave pentacyclotelluroxane consisting of two molecules each
of the starting tellurium oxides. The bulky aromatic substituents
attached to the tellurium atoms efficiently prevent further aggregation
and enable full characterization using multinuclear (1H, 13C, and 125Te) NMR and IR spectroscopy as well
as elemental analysis. For (TipTe)4(Tip2Te)2O10 (3TT, Tip = 2,4,6-triisopropylphenyl),
the molecular structure was unambiguously determined by an X-ray crystallographic
analysis. To estimate the dissociation energies of the tellurinic
anhydride–tellurone adducts, density functional theory calculations
were performed, and it was found that the adducts are highly stabilized
by forming a four di-μ-oxo bridge structure.