Selected chemistry of cyclophosphazenes and cyclothiaphosphazenes

Polymers with Sulfur(VI)−Nitrogen−Phosphorus Backbones: Synthesis, Characterization, and Properties of Atactic Poly[(amino)thionylphosphazenes]

“…Van de Grampel and co-workers have previously reported that when the cyclic thionylphosphazene 1a is treated with primary amines, substitution reactions take place at both the phosphorus and the sulfur centers. , The initial reaction occurs at phosphorus by either a geminal or a nongeminal substitution pathway depending on the amine, solvent, and degree of substitution. The substitution reactions were proposed to proceed via an S N 2 mechanism at phosphorus with the formation of a five-coordinate intermediate, and via an S N 1 type process at the sulfur center. , Aminolysis by primary amines was found to follow the reactivity sequence P(Cl 2 ) > P(Cl, Am) > S(O, Cl) (Am = amino). If considerable steric hindrance was present, as with secondary amines such as diethylamine and piperidine, the reverse sequence S(O, Cl) > P(Cl, Am) was observed.…”

“…Van de Grampel and co-workers have previously reported that when the cyclic thionylphosphazene 1a is treated with primary amines, substitution reactions take place at both the phosphorus and the sulfur centers. 20,21 The initial reaction occurs at phosphorus by either a geminal or a nongeminal substitution pathway depending on the amine, solvent, and degree of substitution. The substitution reactions were proposed to proceed via an S N 2 mechanism at phosphorus with the formation of a five-coordinate intermediate, and via an S N 1 type process at the sulfur center.…”

“…The substitution reactions were proposed to proceed via an S N 2 mechanism at phosphorus with the formation of a five-coordinate intermediate, and via an S N 1 type process at the sulfur center. 20,21 Aminolysis by primary amines was found to follow the reactivity sequence P(Cl 2 ) > P(Cl, Am) > S(O, Cl) (Am ) amino). If considerable steric hindrance was present, as with secondary amines such as diethylamine and piperidine, the reverse sequence S(O, Cl) > P(Cl, Am) was observed.…”

Regioselective Substitution Reactions of Sulfur(VI)−Nitrogen−Phosphorus Rings: Reactions of the Halogenated Cyclic Thionylphosphazenes [NSOX(NPCl2)2] (X = Cl or F) with Oxygen-Based Nucleophiles

“…Whereas the nucleophilic substitution behavior of the cyclic phosphazene [NPCl 2 ] 3 has been studied extensively, similar studies of the reactivity of thionylphosphazenes are much more limited. The reactions of 1 and to a lesser extent 2 with nitrogen-based nucleophiles have been reported and were found to be characterized by the following general order of reactivity: PCl 2 > PCl(NHR) > SOCl for primary amines and PCl 2 > SOCl > PCl(NR 2 ) for secondary amines. , In contrast, no reactions of thionylphosphazenes with oxygen-based nucleophiles have been reported . We therefore examined the reaction of 1 and 2 with several oxygen-based nucleophiles of different basicity and nucleophilicity.…”

“…Inorganic heterocycles have attracted considerable attention because of their interesting structures, bonding, and reactivity, − their applications as precursors to or components of solid state materials, , and their use as precursors to novel polymers via ring-opening polymerization (ROP). − Over the past two decades six-membered cyclic thionylphosphazenes such as 1 have been well-studied, and the skeleton present in these compounds, which consists of four-coordinate sulfur(VI), nitrogen, and phosphorus atoms, has been shown to be robust and stable. , We recently reported that 1 and the fluorinated analogue 2 undergo thermal ROP to yield high molecular weight sulfur(VI)−nitrogen−phosphorus polymers, poly(thionylphosphazenes) ( 3 ), and macrocycles. ,, Reaction of 3 with aryloxide nucleophiles was found to yield moisture stable poly(aryloxythionylphosphazenes) 4 in which the sulfur−halogen bonds remain intact . In contrast, treatment of 3 with primary amines yielded poly(aminothionylphosphazenes) in which the halogen substituents at both phosphorus and at sulfur are replaced .…”