Synthesis, reactivity and structures of spirocyclic products derived from octachlorocyclotetraphosphazene: comparison with spirocyclic cyclotriphosphazenes and linear phosphazenes

Abstract

The reaction of N₄P₄Cl₈ 1 with the difunctional reagents 2,2′-methylenebis(4,6-di-tert-butylphenol) (as its disodium salt) and N,N′-diisopropylpropane-1,3-diamine gave the spirocyclic products 2,2-N₄P₄{[O-4,6-(t-Bu)₂C₆H₂]₂CH₂}Cl₆ 4 and 2,2-N₄P₄[N(i-Pr)CH₂CH₂CH₂N(i-Pr)]Cl₆ 5. Further reaction of 1 with 2 mol equivalents of N,N′-diisopropylpropane-1,3-diamine afforded the novel dispiro derivative 2,2,6,6-N₄P₄[N(i-Pr)CH₂CH₂CH₂N(i-Pr)]₂Cl₄ 6. Whereas the analogous reaction of N₃P₃Cl₆ 2 with the above diamine gave the monospiro derivative 2,2-N₃P₃[N(i-Pr)CH₂CH₂CH₂N(i-Pr)]Cl₄ 7 readily, the reaction of 2 with the diols CH₂[4,6-(t-Bu)₂C₆H₂OH]₂ or CH₂(4-Me-6-t-BuC₆H₂OH)₂ is sluggish. In the case of the latter diol, a product formulated as N₃P₃[O-4-Me-6-t-BuC₆H₂-4-Me-6-t-BuC₆H₂OH]Cl₅ 9 was identified (³¹P NMR). The linear phosphazene Cl₂P(O)NPCl₃ 3, by contrast, reacted with CH₂(4-Me-6-t-Bu-C₆H₂OH)₂ and Et₃N to give the cyclic product Cl₂P(O)NP[(O-4-Me-6-t-BuC₆H₂)₂CH₂]Cl 8. Reaction of the spirocycle 5 with an excess of MeNH₂/Et₃N afforded the new bicyclic phosphazene containing a spirocyclic ring N₄P₄[N(i-Pr)CH₂CH₂CH₂N(i-Pr)](NHMe)₄(NMe) as a crystalline solid. The crystal structures of 4·0.5C₄H₈Cl₂ and 5–8 have been determined.