A λ5‐cylotriphosphazene with nitroxyl groups as model for a paramagnetic poly(organo‐λ5‐phosphazene)

Reaction of hexachlorocyclotriphosphazene (syst. name: 2,2,4,4,6,6‐hexachloro‐1,3,5,2λ5,4λ5,6λ5‐triazatriphosphorine) (1) with 4‐hydroxy‐2,2,6,6‐tetramethylpiperidin‐1‐oxyl (2a) gave the hexa‐substituted λ5‐cyclotriphosphazene 3a. Electron paramagnetic resonance spectra at low concentrations (10−5 mol/L) showed a singlet only (no triplet) due to spin‐spin exchange in the molecule. The paramagnetic molar susceptibility amounts to 7229 · 10−6 cm3/mol at 300 K and does not depend on the magnetic field strength. 3a obeyed the Curie‐Weiss law between 36 and 296 K demonstrating that there is no antiferromagnetic spin exchange.