Synthesis of New Derivatives of Cyclotriphosphazene Substituted with the Salen Side Groups

The reaction between hexachlorocyclotriphosphazenes (N3P3Cl6) and three equivalents of bis-salicylidene ethylene diamine (HOC6H4-CH=N-CH2-)2 (salen) was investigated in two different experimental conditions. In the presence of anhydrous Na2CO3 in stirring tetrahydrofuran (THF) medium, the reaction led to a 50:50 mixture of tris[bis(salicylidene)ethylenediamine] cyclotriphosphazene, spiro-N3P3[(OC6H4-CH=N-CH2-)2]3 (1) and ansa (2) fully substituted products, whereas, in toluene solution, N3P3Cl6 with salen (3) and Al2O3/KOH afforded the spiro (1), as the only isolable compound. The spectroscopic data revealed that the oxygen atoms of salen moieties were selectively bonded to the three phosphorus atoms of the phosphazene ring. The new derivatives of cyclotriphosphazenes were characterized by IR spectrophotometry 1H NMR, 31P NMR spectral data and elemental analysis.