Synthesis and structure of aluminium amine-phenolate complexesCCDC reference numbers 729812–729816. For crystallographic data in CIF or other electronic format see DOI: 10.1039/b904534a.

Reaction of Al(OiPr)3with the tris-phenol amine ligand L1H3in toluene at ambient temperature results in the formation of the iso-propanol adduct [HOiPr·Al(L1)]. Single crystal X-ray diffraction analysis reveals the structure to be a hydrogen bonded dimer. Reaction of Al(OiPr)3(or AlMe3) with L1H3in THF affords the related, and structurally characterised THF adduct, [THF·Al(L1)]. Similar reaction of Al(OiPr)3(or AlMe3) with the bis-phenol amine and tetra-phenol diamine ligands, L2H3and L3H4, results in the formation and isolation of the complexes [Al(L2)]2and [Al(L3)H] respectively, both of which have been structurally characterised viasingle crystal X-ray diffraction studies. Reaction of the alkoxide bridged dimer [Al(L2)]2with the strong Lewis base HMPA results in the formation of the monomeric HMPA adduct [HMPA·Al(L2)] which was also structurally characterised. The adduct [HOiPr·Al(L1)] and the dimer [Al(L2)]2were 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 h produced narrow molecular weight polymer (24 h: yield = 25%, Mn= 14500 and PDI = 1.05; 48 h: yield = 65%, Mn= 47700 and PDI = 1.06). [ABSTRACT FROM AUTHOR]