Cyclophosphazene derivatives

Reactions at the exocyclic position of cyclophosphazene derivatives represent a means for widely expanding the range of available phosphazenes. The synthesis of covalently bound cyclophosphazene heme complexes starts with N3P3 (OPh), -Cl which is converted to N3P3(OPh)5NMeCH2CH2CN. Following reduction of the... 

In selected cases, the effect of solvation on the crystalline structure formed is, however, considerably more pronounced. For example, the observed packing in the crystal of 2,4,6-tris( 1,3-propylenediamine-N,N -)cyclotriphosphazene (4) dihydrate (Fig. 6) is due to strong intermolecular hydrogen bonds between molecules of water and suitable couples of N-H groups on the host moiety M). The HzO species form also continuous H-bonded layers of solvation around the cyclophosphazene derivatives, thus stabilizing the crystal lattice. 

Fragmentation of amino acid-derived spirophosphorane 128 has been analyzed using field desorption (FD), El, and Cl mass spectrometry <1997RCM1825, 1997CCL629>. In spiro-crypta cyclophosphazene derivatives 129, the major decomposition pathway involved the initial cleavage of a P-Cl bond rather than cleavage of an exocyclic P-N bond as is normally seen for cyclophosphazenes <2004JST139>. 

Proton NMR has been extremely valuable in the structural elucidation of cyclophosphazene derivatives containing alkylamino, alkoxy or simple alkyl substituents [287]. 

Fig. 10. Some of the ring conformations adopted by the eight membeied cyclophosphazene derivatives...

A cyclophosphazene derivative was used as a linking agent to produce miktoarm stars consisting ofPS and Nylon-6 branches [50], according to Scheme 18. 

There are also other reports of metal complexes of cyclophosphazene derivatives, but in most cases the structures of the complexes have not been established with certainty (21, 150, 229, 231, 357, 386). 

There are many reactions of cyclophosphazene derivatives involving substitution or transformations at side chains that do not affect the... 

The structures of a large number of cyclophosphazene derivatives have been determined by X-ray diffraction, and the data obtained have helped to clarify the nature of the bonding in this class of compounds. Corbridge (125) has recently reviewed this work. 

As a result of the extensive compilation of basicity data for cyclo-triphosphazenes, it has been possible to evaluate substituent constants for different groups (2 78-180). These constants, can be used to calculate the pKa value of a cyclophosphazene derivative containing one or more substituents (179, 180). Hence, a comparison of calculated and observed pKa values can often provide information for the complete characterization of a derivative (180). Basicity data for cyclotetrapho-sphazenes and higher homologs are limited (175, 321), and substituent constants have not been evaluated. 

The theory proposed by Dewar et al. (154) is also based on a tr-bonded P—N skeleton of sp2-hybridized nitrogen and sp3-hybridized phosphorus but postulates a pair of linear combinations of phosphorus dxz and dy orbitals for overlap with an adjacent nitrogen p2 orbital. The result is a system of almost independent three-center 7t-bonds containing two phosphorus atoms and one nitrogen atom (Fig. 18). More detailed calculations appear to support this theoretical treatment (167,168,171, 172, 318) and indicate that conjugation beyond the three-center islands is of minor importance in cyclotriphosphazene derivatives (167). X-Ray crystallographic data for heterogeneously substituted cyclophosphazene derivatives (Section V,C) and evidence... 

Cyclophosphazene derivatives, (NPR2)4 (R = Me, NHMe) and the polymeric phosphazene, [NP(NHMe)2] react with K2PtCl4 in organic media to yield square-planar complexes, (NPR2)4 PtCl2 and a product... 

Applications of polyphosphazenes as flame retardants, electrolytes for special batteries, and biomaterials have been described. Some cyclophosphazene derivatives can serve as hosts for small molecule Clathration. ... 

The synthesis of new cyclophosphazene derivatives by reactions of the exocyclic groups now represents a major route to these materials. 

A particularly large number of applications of cyclophosphazene derivatives has been noted. Of particular interest is the large number of reports focusing on methacryloyloxyethoxy derivatives, typically N3Pj(0CH2CH20C(0)C(Me)=CH2) j. Uses claimed for derivatives center on the easy cure which can be accomplished due to the reactivity of the appended methacrylate. Several reports focus solely on the preparation of the hexasubstituted derivative either from 2-hydroxyethylmethacrylate and (NPCl2)3 or by two step indirect routes which have been... 

Studies of the application of cyclophosphazene derivatives find a broad interest and comprise many areas, such as multifunctional initiators, biological materials, lubricants and flame-retardants. 

Controlled radical polymerization of styrene has been carried out in the presence of cyclophosphazene derivatives of 4-hydroxy-2,2,6,6-tetramethyl-piperidin-l-one (4-hydroxy-TEMPO). Hexafunctional compounds, N3P3[OC6H4(CH2Br-4)]6, N3P3 0C6H4[CH20C(0)CH(Me)Br-4]>6 and... 

The reactions of halophosphazenes with nucleophiles continues to be utilized as one of the major routes to new cyclophosphazene derivatives. Fluorophos-phazenate anions are obtained by the reactions of fluorocyclophosphazenes with (Me2N)3S Me3SiF2l, an effective fluoride ion donor. The trimer yields 10 as the... 

---