Phosphorus–nitrogen compounds. Part XXI. Alkylthio- and phenylthio-cyclotriphosphazatrienes

Abstract

By means of sodium alkanethiolate (or benzenethiolate) a representative series of alkylthio (or phenylthio)cyclotriphosphazatrienes, N₃P₃Cl_6–n(SR)_n, have been prepared and characterised. Very much more pronounced than in alcoholysis or aminolysis, the degree of chlorine replacement in alkanethiolysis is markedly dependent on the reaction conditions. With the alkanethiolates (R = Alk) bis-, tetrakis-, and hexakis-alkylthio-derivatives (n= 2, 4, or 6) are the predominant reaction products; small quantities of trisalkylthio-derivatives (n= 3) were also observed. With sodium benzenethiolate (R = Ph) the differentiation in reactivity between different degrees of replacement is less marked, and only bis- and hexakis-derivatives (n= 2 or 6) were obtained. In contrast to the corresponding hexa-alkoxy-derivatives, N₃P₃(OAlk)₆, the hexakisalkylthiocyclotriphosphazatrienes, N₃P₃(SAlk)₆, could not be rearranged to the isomeric cyclotriphosphazanes. The structures of the alkylthio(or phenylthio)phosphazenes are discussed, as are the factors influencing the degree of chlorine replacement and the mechanism of the alkanethiolysis (benzenethiolysis).