Phosphorus–nitrogen compounds: part 16. Synthesis, stereogenism, anisochronism and the relationship between 31P NMR spectral and crystallographic data of monotopic spiro-crypta phosphazene derivatives

Abstract

The condensation reactions of N2O3-donor type coronands (1–3) with hexachlorocyclotriphosphazatriene, N3P3Cl6, resulted in the formation of spiro-crypta phosphazene derivatives (4–6). These compounds with excess morpholine and 1,4-dioxa-8-azaspiro[4,5]decane (DASD) afford fully substituted morpholino (7 and 10) and 1,4-dioxa-8-azaspiro[4,5]deca (8)-substituted phosphazene derivatives, respectively. Whilst, in the same conditions, the reactions of 4, 5 and 6 with pyrrolidine, morpholine and DASD also produce partially pyrrolidino-substituted geminal (9 and 11), mono-substituted pyrrolidino (12), morpholino (13) and 1,4-dioxa-8-azaspiro[4,5]deca (14) phosphazenes. It has been clearly observed that the chloride replacement reactions of 4, 5 and 6 with pyrrolidine lead to the geminal products. Compounds 7, 8 and 10 are the first examples of anisochronic tetrakis (amino) phosphazenes according to 31P NMR data. The structures of 7, 8 and 10–14 have been determined by FTIR, MS, 1H, 13C and 31P NMR, DEPT, and HETCOR spectral data. The solid-state structures of 9, 13 and 14 have been examined by X-ray diffraction techniques. The sums of the bond angles around the spiro cyclic nitrogen atoms [344.8(4)° and 347.6(4)°] of 9, indicate that the nitrogen atoms have pyramidal geometries. Thus, the N atoms seem to have stereogenic configurations. Compounds 12–14 also have two stereogenic P-atoms, and they are expected to be in the mixture of enantiomers. The relationships between NPN (α and α′) bond angles and δPspiro values and the correlation of Δ(P–N) with δPspiro and Δ(δP) values are presented.