Synthesis and Reactivity of Cyclotriphosphazenes Bearing Reactive Silane Functionalities: Novel Derivatives via Hydrosilylation Reactions

Cyclotriphosphazenes with the general structure N₃P₃(OPh)₅NH(CH₂)₃SiMe₂OEt react with lithium aluminum hydride in diethyl ether to produce N₃P₃(OPh)₅NH(CH₂)₃SiMe₂H. Subsequent reaction of this species with alkenes in the presence of a platinum catalyst produced new cyclotriphosphazenes bearing alkoxy, siloxy, glycidyl, and ferrocenyl side groups. The yields depended on the type of catalyst and olefin used. Tetramethyl-1,3-divinyldisiloxane-platinum complex (DVDS:Pt) was a more efficient hydrosilylation catalyst than hydrogen hexachloroplatinic acid (CPA). Use of the latter catalyst yielded the silanol N₃P₃(OPh)₅NH(CH₂)₃SiMe₂OH, as a side product. This derivative subsequently condensed to produce a ring-linked phosphazene species. The hydrosilylation products were studied by ³¹P, ¹H, and ¹³C NMR and infrared spectroscopy, elemental analysis, and mass spectrometry. Analogous reactions were investigated with the high-polymeric counterparts. Polymers with the general structure [NPRi₈(NH(CH₂)₃SiMe₂OEt)_0.2]_n, where R is -OCH₂CF₃ or -OC₆H₅, were synthesized and allowed to react with LiAlH₄. The reduction process induced significant molecular weight decline from phosphorus-nitrogen bond cleavage, which was probably initiated by coordination of the aluminum to the nitrogen atoms in the polymer backbone and the amino side group. The influence of complexing agents, such as 4-(dimethylamino)pyridine (DMAP) and Et₃N, on the reduction reactions was investigated.