POLYCONDENSATION OF TRIS(TRIMETHYLSILYLSELENO)PHOSPHANE

Tris-(trimethylsilyl)phosphane and their organo substituted derivative s (Me3Si)(3-n)P(Me3C)(n) (n: 0, 1, 2) (1a-c) had been found suitable f or the insertion of selenium' into the phosphorus-silicon bond. At dee p temperatures all silylselenophosphanes of the series (Me3SiSe)(3-n)P (Me3C)(n) (2a-c) are formed in a nearly quantitative reaction, if no e xcess selenium is present. (Me3C)(Me3SiSe)(2)P=Se (3b) and (Me3C)(2)(M e3SiSe)P=Se (3c) are detectable in small quantities as the only by-pro ducts of the reaction of(lb-c), whereas (la) end in the formation of ( 2a) and traces of the dimer (Me3SiSe)(2)P-P(SeSiMe3)(2) (4). On exposu re to light or at elevated temperatures (2a) undergoes a disproportion ation, forming Se=P(SeSiMe3)(3) (3a), and the heterocycles P3Se4(SeSiM e3) (5) and alpha-P4Se3(SeSiMe3)(2) (6). (Me3Si)(2)Se is split off as a condensation product. After further irradiation or prolonged standin g at room temperature, an insoluble oligomer is formed. The constituti ons of (2-6) were determined by the analysis of their P-31- and Se-77- nmr spectra.