Aluminum(III) complexes containing O,O chelating ligand

Abstract

The stoichiometric reactions of trimethylaluminum with 2,6-(MeOCH 2 ) 2 C 6 H 3 OH (LH) revealed compounds L 3 Al (1) and L 2 AlMe (2). On the other hand reaction of 1 equiv. of LH with trimethylaluminum did not lead to the formation of complex LAlMe 2 (3), rather 2 together with Me 3 Al were observed as a result of a disproportionation of 3. Compounds 1 and 2 were characterized by elemental analysis, 1 H and 13 C NMR spectroscopy and in the case of 1 by X-ray diffraction. Derivative 2 underwent transmetalation with Ph 3 SnOH, giving LSnPh 3 (4) as the result of a migration of ligand L from the aluminum to the tin atom. The identity of 4 was established by elemental analysis, 1 H, 13 C and 119 Sn NMR spectroscopy and 1 H, 119 Sn HMBC experiments. The system 2 and B(C 6 F 5 ) 3 in a 1 : 1 molar ratio was shown to be active in the polymerization of propylene oxide and ε-caprolactone.

Metal catalysts for ε-caprolactone polymerisation

“…17) was moderately active for 3-caprolactone polymerisation, reaching 13% conversion after 24 h at room temperature and for a monomer : metal ratio of 1,000 : 1. 143 Following our early reports on the catalytic improvement in ethylene polymerisation when shifting from a calixarene to an oxacalixarene supported complex, 134 our group investigated the use of the mixed alkyl/alkoxide zinc complex 265 (Fig. 18).…”