| Abstract: | Concerning the Thermal Behaviour of Partially Silylated Tri- and Tetraphosphanes The influence of Me3Si- and Me3C-substituents in the compounds (Me3Si)PP(SiMe3)(CMe3)]2 1 , (Me3C)2P-P(SiMe3)? P(SiMe3)2 2 , (Me3C)2P? P(SiMe3)? P(SiMe3)(CMe3) 3 , (Me3Si)PP(CMe3)2]2 4 , (Me3C)(Me3Si)P? P(SiMe3)]2? P (SiMe3)(CMe3) 5 , (Me3C)(Me3Si)P? P(CMe3)]2? P (SiMe3)(CMe3) 6 and (Me3C)2P? P(SiMe3)]2? P (CMe3)2 7 on their thermal stability as well as on the reactions that occur, when these compounds are exposed to higher temperatures, is investigated. The tetraphosphane 6 , bearing 4 Me3C and 2 Me3Si groups (the latter being located at the primary P atoms) hardly shows any changes, when it is exposed to 100°C in toluene (hermetically sealed ampoule) for several days, while the remaining compounds are found to rearrange significantly under similar conditions. Thus 1 no (Me3C)2P-group] forms trans- P4 (SiMe3)2(CMe3)2 9 , while (Me3C)P(SiMe3)2 8 is being cleaved off, which can be understood easily, assuming the formation of the corresponding linear pentaphosphane (accompanied by the cleave-off of 8 ) and its subsequent cyclisation to 9 (again splitting off 8 ). 5 is found to form cyclophosphanes (tri-, penta-, hexa-), while (Me3C)P(SiMe3)2 and P(SiMe3)3 are being cleaved off. All of the remaining compounds mentioned with (Me3C)2P-groups] finally yield, aside of P(SiMe3)3 and (Me3C)P(SiMe3)2, the cyclophosphanes P4P(CMe3)2]4 11 and P3P(CMe3)2]3 12 , which can be explained by the formation of the reactive intermediate (Me3C)2P? \documentclass{article}\pagestyle{empty}\begin{document}$\mathop {\rm P}\limits_ - ^ - $\end{document} ( which, however, has not been proven). |
