Cyclophosphazenes cyclotriphosphazenes

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. 

Chiral spermine-bridged cyclotriphosphazenes 21 have been synthesized by the reaction of a gi r -disubstituted cyclophosphazene 188 with spermine (Equation 34). The chiral products are also accessible by derivatizing a spermine-bridged cyclophosphazene <2002JCD365>. 

Another class of inclusion complexes containing phosphorus in the host structure are cyclophosphazenes. Sozzani and co-workers have reported 31P CP/MAS studies of two organic derivatives tris(o-phenylene-dioxy)cyclotriphosphazene (TPP) and tris(2,3-naphtalene-dioxy)cyclotri-phosphazene (TNP). In the cited works, SS NMR technique was employed to recognise guest-free TNP matrix and of ICs with guests, for example benzene, tetrahydrofuran and p-xylene. The 31P NMR spectra were particularly informative regarding the symmetry of the phos-phazene ring. 

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... 

Cyclophosphazenes with macrocyclic ligands form a part of a general review about supramolecular interactions in synthetic procedures. The correlation between structure and NMR ( C and P) parameters for tris(2,3-naph-thalenedioxy)cyclotriphosphazene and tris(o-phenylenedioxy)cyclotriphos-phazene has been reviewed. ... 

Synthesis and polymerization of multifunctional cyclotriphosphazenes have been described <04PS%1>. A series of new nongeminal cyclophosphazenes 52 has been prepared via deprotonation-substitution reactions at the methyl groups of both cis and trans isomers of cyclotriphosphazene 51 with different electrophilic reagents <04PS817>. 

Theoretical and experimental approaches to understanding structure and properties of cyclophosphazenes have appeared. The most significant of these is a report of the observed (x-ray diffraction) and calculated (ab initio) deformation electron densities in the benzene solvate of hexa(aziridinyl)-cyclotriphosphazene. The electron densities in the phosphazene clearly show the classic island model pattern with nodes in the n system at nitrogen. The dual system is also clearly... 

Other effective hosts are cyclophosphazenes, such as /rw(6>-phenylenedioxy)cyclotriphosphazene (Fig. 3h) and... 

An extended review has appeared on advances in the chemistry of chlorocy-clophosphazenes. Another review describes the role of cyclophosphazenes as polymer modifiers with emphasis on 2-oxazoline and epoxy derivatives. A short review has been published on the physical properties of the host-guest adducts involving tris(o-phenylenedioxy)cyclotriphosphazene (TPP) (141) as host. ... 

---