Synthesis of isoxazolylphosphazene

The reaction of phosphonitrilic dichloride cyclic trimer (1) with 4-hydroxymethyl-3,5-disubstituted isoxazoles leads to incomplete substitution, and forcing conditions gave rise to fragmentation to the corresponding 4-chloromethylisoxazole derivatives. Two carbon homologation of the C-4 isoxazole moiety, followed by reaction with (1) produced the hexakis-substitution product (9). Preliminary studies indicate that (9) functions as a ligand in complexes with Co(II), Cr(III) and Mn(III).