Reaction of Al(OiPr)3 with the tris-phenol amine ligand L1H3 in toluene at ambient temperature resultsin the formation of the iso-propanol adduct HOiPr·Al(L1). Single crystal X-ray diffraction analysisreveals the structure to be a hydrogen bonded dimer. Reaction of Al(OiPr)3 (or AlMe3) with L1H3 inTHF affords the related, and structurally characterised THF adduct, THF·Al(L1). Similar reaction ofAl(OiPr)3 (or AlMe3) with the bis-phenol amine and tetra-phenol diamine ligands, L2H3 and L3H4,results in the formation and isolation of the complexes Al(L2)2 and Al(L3)H respectively, both ofwhich have been structurally characterised via single crystal X-ray diffraction studies. Reaction of thealkoxide bridged dimer Al(L2)2 with the strong Lewis base HMPA results in the formation of themonomeric HMPA adduct HMPA·Al(L2) which was also structurally characterised. The adductHOiPr·Al(L1) and the dimer Al(L2)2 were tested for their activity in the ring-opening polymerisation(ROP) of rac-lactide under solvent-free conditions (130 C). Under the conditions employed Al(L2)2failed to produce polymer after 48 h, in stark contrast to HOiPr·Al(L1) which after 24 h and 48 hproduced narrow molecular weight polymer (24 h: yield = 25, Mn = 14500 and PDI = 1.05; 48 h:yield = 65, Mn = 47700 and PDI = 1.06).
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