THE FIRST ORGANOALUMINUM DERIVATIVE OF A HYDROXY CARBOXYLIC-ACID - MOLECULAR-STRUCTURE OF THE TETRANUCLEAR [ET2AL](4)[(MU-O2C)C6H4-2-MU-O](2) ADDUCT

The reaction of triethylaluminum with salicylic acid in a 2:1 molar ra tio results in the formation of the novel tetranuclear diethylaluminum aryloxide carboxylate adduct [Et2Al](4)[(mu-O2C)C6H4-2-mu-O](2) (1). Compound 1 has been characterized by elemental analysis and H-1 and Al -27 NMR and IR spectroscopy, and its molecular structure has been dete rmined by X-ray crystallography. The molecule is a centrosymmetric clu ster with a skeleton framework consisting of three fused heterocycle r ings, one 12- and two 6-membered. The two diethylaluminum units symmet rically join the two salicylic acid dianions by the formation of bridg es between the aryloxide oxygen atom and one carboxylate oxygen. atom of the second ligand. The two other diethylaluminum units are chelated by the aryloxide and second carboxylate oxygen atoms of each ligand. The carboxylate groups display a bidentate coordination mode with syn- anti conformation. The binding mode of the carboxylate and alkoxide li gands to metal centers is also discussed.