Cyclophosphazene

Sulfanuric halides contain the characteristic group -N=S(0)X- (X = Cl, F). Unlike the isoelectronic cyclophosphazenes (NPClajx (x = 3-17), " only six-membered rings have been well characterized. The sulfanuric halides are colourless solids (X = Cl) or liquids (X = F), which are stable in dry air. Sulfanuric chloride [NS(0)C1]3 is best prepared by treatment of SOCI2 with sodium azide in acetonitrile at -35°C (Eq. 8.16). It may also be obtained as a mixture of a- and yS-isomers in a two-stage reaction from H2NSO3H and PCls. The fluoride [NS(0)F]3 is formed as a mixture of isomers by the fluorination of [NS(0)C1]3 with Sbp3. ... 

Mechanism of phase-transfer phenolysis of chlorinated cyclophosphazenes 99MI20. 

Cyclopentene-l-dithiocarboxylic acid, 2-amino-meta complexes, 2, 800 Cyclophane chlorophylls, 3, 58 Cyclophane hemes iron complexes, 4,1269 Cyclophosphazenes metal complexes, 2, 81 Cyclopropane carbonylation... 

The diazaphosphane or aminoiminophosphane ligands with a NPN framework are another subclass of cyclophosphazenes. These compounds with both phosphorus in oxidation state (111) [104-110] and (V) [111-112] have been employed in the synthesis of four membered heterocycles and coordination chemistry with group 13 derivatives. Several complexes of trivalent phosphorus derivatives with both aluminum halide and alkyls are known as illustrated for 48 in Scheme 21 [113-119]. The structure determination of 48 confirms the formation of a four membered metallacycle [116, 117],... 

Process III Preparation of Polyphosphazenes by Ring Opening Polymerization Processes of Substituted or Partially Substituted Cyclophosphazenes... 

The problem of the thermally induced polymerization reaction of partially or completely substituted cyclophosphazenes has been considered in the past by several authors [355-357], and more recently by H. R. AUcock [358]. This is because of the ease of synthesizing these substrates, the possibihty of preparing structurally regulated poly(organophosphazenes), and the lack of any additional nucleophilic substitution processes on the poly(organophosphazenes) obtained by the ROP process of fully saturated trimers. 

When the ROP process is attempted on partially or completely substituted cyclophosphazenes in molten state several phenomena can take place ... 

The occurrence of one of these situations rather than another depends on the chemical nature of the cyclophosphazene exploited and on the experimental conditions selected for the polymerization process. These facts are illustrated in Table 3. 

Table 3 Influence of experimental parameters on the reactivity of partially or completely substituted cyclophosphazenes during a ROP process...

An important comprehensive review of the cyclophosphazenes (including dimeric monophosphazenes) has appeared. 

Derivatives of the type, RjP N=P(NH2)X 2, were obtained by displacement of the chlorine atoms marked with an asterisk by ammonia. The parent halides decomposed at ca. 150 °C giving, amongst other products, cyclophosphazenes, (NPR2) , and phosphazene polymers. 

Examples of cyclophosphazenes with ring systems containing elements other than phosphorus or nitrogen continue to be reported. The linear phosphazene [Ph2(H2N)Pi N.i P(NH2)Ph2]+Cl is cyclized by antimony pentachloride to give the compound (35). This result contrasts with... 

An interesting series of ammonolysis and aminolysis products has been obtained from the cyclophosphazene (36) (see Scheme 2). It is note-... 

The reactions of alkylaminofluorocyclophosphazenes with hydrogen halides have provided a route to cyclophosphazenes with mixed halogen substituents ... 

The use of n-butylamino-derivatives of cyclophosphazenes in flame-proofing cellulose-based fabrics has been described in a patent application. The topic of fiame retardants is also covered in a recent review, where phosphazenes are important because of their relatively high phosphorus and nitrogen contents. 

B. Alkoxy- and Aryloxy-derivatives.—The preparation and physical properties of a series of thermally stable monoalkoxy (or aryloxy) fiuoro-cyclophosphazenes have been reported ... 

Mention has already been made of the application of alkoxycyclophos-phazenes, [NP(OR)2] , as flame retardants in rayon. Although the methoxy-derivatives, with their high phosphorus content, were expected to be most efficient in this respect, their water solubility proved a major shortcoming. However, the n-propoxy series, [NP(OPr )2] ( mainly 3—6), were found to impart excellent flame resistance and were well retained by rayon. The cyclophosphazene alkoxides were obtained by the addition of sodium-n-propoxide to the chloride homologues, (NPCl2)n, and were added to the viscose dope before the rayon was spun. The flame resistance imparted by various amino- and thioalkoxy-derivatives was also tested, but found to be inferior to the results obtained with alkoxy-deriva-tives. Several patent applications have resulted from work on this topic. ... 

The first example of an optically active cyclophosphazene (54) has been obtained by elegant experimental work. The route chosen is summarized in Scheme 5. 

Labarre, J.-F. Natural Polyamines-Linked Cyclophosphazenes. Attempts at the Production of More Selective Antitumorals, 129, 173-260 (1985). 

V. Cyclophosphazene-Based Ligands and their Coordination Chemistry... 

Cyclophosphazenes are a fascinating group of inorganic heterocyclic compounds whose chemistry is multi-faceted, well developed and reasonably well understood. They are closely related to the linear poly-phosphazenes this relationship is unlike any other existing between ring-polymer systems. Although cyclic siloxanes and polysiloxanes have a close interrelationship, the number and types of cyclophospha-zene derivatives that are known, together with their exact counterparts in polyphosphazenes, underscore the utility of cyclophosphazenes as models for the more complex polyphosphazenes. The literature on cyclophosphazenes has appeared earlier in the form of books (1,2), chapters of books (3-5), authoritative compilations of data (6,7), and several reviews (8-21). The current literature on this subject is reported annually in the Specialist Periodic Reports published by the Royal Society of chemistry (22). This review deals mostly with chlorocyclo-... 

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