Synthesis of the First Stable Pentaco-Ordinate 1,2-Thiaphosphetene

Pentacoordinate 1,2-thiaphosphetenes bearing the Martin ligand were synthesized by the reaction of the corresponding phosphorus ylide with isothiocyanates. Their mass and NMR spectral data showed that they have 1:2 adducts of the phosphorus ylide and isothiocyanates, which have a distorted trigonal bipyramid with oxygen and sulfur atoms at the apical positions. Thermolysis of the phenyl isothiocyanate adduct gave the corresponding cyclic thio-phosphinate as a phosphorus-containing product in almost quantitative yield.