Synthesis and structure of diethylaluminum malonate: An unusual hexanuclear aluminum complex with malonate trianion ligands

Reaction of malonic acid with Et3Al results in the formation of the hexanuclear aluminum compound Et12Al6[CH(COO)2]2(THF)2 (1) containing malonate trianion ligands. Molecular studies showed that the centrosymmetric molecule of 1 consists of a tricyclic structure formed by a central four-membered Al2O2 ring and two six-membered AlO2C3 rings. All the aluminum atoms are four-coordinate. The compound showed low activity as an initiator of ɛ-caprolactone polymerization.