YLIDYLPHOSPHORUS SULFIDES, SELENIDES, DIS ULFIDES, SULFIDE SELENIDES,AND DISELENIDES

We report on the first stable monomeric phosphorus monochalcogenides 2 , 8 and the first stable dichalcogenides 4, 10 without bulky or intram olecularly coordinating substituents. They are stabilized by a high co ntribution of the zwitterionic resonance formula, which follows both f rom the NMR spectra and from an X-ray structure determination. Their p reparation starts from triphenylphosphoniumylidyl-dichlorophosphanes 1 . For the monochalcogenides they are treated with sodium sulfide or se lenide or better with bis(trimethylsilyl) sulfide or selenide. In case of the C-phenyl and C-meta-tolyl representatives and also of the C-tr imethylsilyl compound a number of secondary, partly novel products are obtained. - The dichalcogenides result from the reaction with sodium disulfide and diselenide, respectively, or from the oxidation of the m onochalcogenides. - Alkylation of the monochalcogenides results in yli dylalkylchalcogenophosphenium salts 13, 15. In solution they are in eq uilibrium with more or less of the covalent form 14, 16, depending on the anion and on the solvent. Alkylation is often accompanied by secon dary reactions. A diselenide loses selenium on alkylation.