Synthesis of Al(III) silsesquioxane complexes and their exploitation for the ring opening polymerisation of rac-lactide

In this paper we report the synthesis and characterisation of silsesquioxane tethered Al(III) complexes. The complexes have been characterised by multi-nuclear NMR spectroscopy and depending upon the bulk of the ligand either Al(L)Me2 or Al(L)2Me complexes were isolated. We also report the first solid-state structure of a tethered Al–silsesquioxane complex of the form Al(L)Me2. All complexes and heterogeneous analogues were tested for the ring opening polymerisation of rac-lactide, with narrow molecular weight polylactide formed.

Graphical abstractThe synthesis, characterisation and catalytic activity of a series of aluminium silsesquioxane complexes together with their heterogeneous counterparts are investigated.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We describe the X-ray structure of a tethered Al(III)–silsesquioxane complex. ► The complexes have been applied for the ring opening polymerisation of rac-lactide. ► Heterogeneous Al(III) complexes have been prepared for the same polymerisation.