Aryl cyclophosphazenes

Cyclization of linear fragments is one of the successful synthetic methods of preparing alkyl- or aryl-substituted cyclophosphazenes. An excellent synthon of this type is the Bezman s salt... 

In contrast to the organo lithium and Grignard reagents Friedel-Crafts arylation reactions occur quite cleanly with N3P3CI6, while unsubstituted fluorocyclophosphazenes do not undergo Friedel-Crafts arylation at all [1,13]. Friedel-Crafts arylation predominantly results in geminal products irrespective of the starting cyclophosphazene (Eq. 42) [229] ... 

Both colourless and deeply coloured compounds are found among the common unsaturated heterocyclic inorganic systems. For example, borazine B3N3H6 (see Section 4.1.2.1), like benzene, is a colourless liquid which exhibits a strong absorption band in the UV region. Similarly, cyclophosphazenes (NPX2) ( = 3-6 X = halogen, alkyl, aryl, alkoxy, dialkylamino) are also... 

These compounds contain the characteristic group -N=S(0)X- (where X = Cl, F, alkyl, aryl, or R2N). Unlike the isoelectronic cyclophosphazenes, only six-membered rings have been well characterized. The sulfanuric halides are colorless solids (X = Cl) or liquids (X = F), which are stable in dry air. Sulfanuric chloride is best prepared by treatment of SOCI2 with sodium azide (equation 26). It may also be obtained as a mixture of a- and /3-isomers in a two-stage reaction from H2NSO3H and PCI5. The fluoride, [NS(0)F]3, is formed as a mixture of isomers by the fluorination of [NS(0)C1]3 with SbF3. 

Two new procedures have been developed for the preparation of aryl and hetero aryl substituted cyclophosphazenes with a direct P-C bond, viz. via the reaction of 9,9,9-trichloro-9-phosphafluorene with NH4CI in refluxing CeHsCl yielding (106), or via treatment of H2NP(0)Ar2 (Ar = aryl residue) with Appel s reagent (PPh3, EtN3, CCU). ... 

Alkyl and Aryl Derivatives.—No new routes to alkyl-substituted cyclophosphazenes have been described, although trimeric and tetrameric homologues can be inter-converted on heating... 

Unlike the isoelectronic cyclophosphazenes only six-membered rings have been well characterized for oligomers of the —NS(0)E— (E = F, Cl, alkyl, aryl or R2N) monomer unit. The trimeric chloride is best prepared by treating of SOClj with sodium azide in... 

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