Synthesis, spectroscopic and structural characterization of tertiary phosphine tellurium dihalides Et3PTeX2 (X = Cl, Br, I)

The reactions of triethylphosphine telluride with SO2Cl2 or I-2 produced the first structurally characterized tellurium-containing tertiary phosphine chalcogen dihalides, Et3PTeCl2 and Et3PTeI2, respectively, in good yields. The corresponding dibromide, Et3PTeBr2, was obtained by an in situ reaction between Et3PTeCl2 and two equivalents of Me3SiBr. This series of compounds has been characterized in the solid state by X-ray structural analyses and in solution by multinuclear NMR spectra. The structures of Et3PTeX2 ( X = Cl, Br, I) all show a T-shaped geometry around tellurium with weak Te center dot center dot center dot halogen interactions giving rise to centrosymmetric dimers. NMR data indicate that Et3PTeI2 exhibits the weakest P - Te bond in solution. The ionic complexes, [(Et3PO)(2)H](2)[Te2I6] and [(Et3PO)(2)H](2)[TeI4], were isolated from THF solutions of Et3PTeI2 and characterized by X-ray structural determinations.