Abstract

4,8,12-Trioxaphosphangulene is a bowl-shaped phosphorus-containing π-conjugated molecule whose molecular geometry is highly sensitive to the substituent attached to the phosphorus atom. Herein, we report the synthesis of a new tungsten pentacarbonyl complex of a chiral 4,8,12-trioxaphosphangulene bearing three phenylethynyl groups. The complex was prepared by coordination of the phosphine center to an in situ generated W(CO)5 fragment and was characterized by multinuclear NMR spectroscopy and elemental analysis. The NMR spectra revealed that the phosphangulene framework retains its threefold symmetry in solution. Comparison of the NMR parameters with those of a previously reported phosphangulene–tungsten complex indicates that incorporation of the phenylethynyl substituents has little effect on either the coordination environment around the phosphorus atom or the phosphine–tungsten interaction. These findings demonstrate that the characteristic bowl-shaped phosphangulene framework is preserved upon tungsten coordination despite π-extension of the molecular framework.

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