Dimethylaluminium iminophosphoranylenamides and iminophosphoranylanilides: Synthesis, characterisation, and their controlled ring-opening polymerisation of epsilon-caprolactone

A series of aluminium iminophosphoranylenamide complexes, [Me2Al{N(Ar)C(Ph)=CHP(Ph-2)=N-Ar-1}] (Ar = Ph, Ar-1 = p-MeC6H4 (9); Ar = Ph, Ar-1 = o-ClC6H4 (10); Ar = Ph, Ar-1 = o-FC6H4 (11); Ar = p-MeC6H4, Ar-1 = o-FC6H4 (12)), were synthesised by the reactions of ArN=C(Ph)CH2P(Ph-2)=NAr1 (5-8) with AlMe3 in toluene. Similar reactions between o-{ArN=P(Ph-2)}C6H4NHC(Ph)=CHP(Ph-2)=NAr (Ar = p-MeC6H4, 13), and AlMe3 in toluene generates aluminium iminophosphoranylanilide, 14. All new compounds were characterised by NMR spectroscopy and elemental analysis. The molecular structures of complexes 9 and 14 were further characterised by single-crystal X-ray structure determination. In the presence of benzyl alcohol (BnOH) each of the complexes is catalytically active for the ring-opening polymerisation (ROP) of epsilon-caprolactone (epsilon-CL), and complex 14 has the highest activity among them.