A structural study of dimethylaluminum carboxylato and hydrazonato complexes

The reaction of trimethylaluminum with 2,4,6-triphenylbenzoic acid and the isoelectronic fluoren-9-one phenylhydrazone results in the formation of the dialkylaluminum complexes [(CH3)2Al{μ-O2CPh(Ph3)}]2 (4) and [Me2AlN(C6H5)NC13H8]2 (5). The synthesis of these complexes, as well as their spectroscopic and structural characterization are reported. X-ray crystallographic studies show that the carboxylato complex 4 adopts a dimeric structure containing an 8-membered O–Al–O–C core whereas the hydrazonato complex 5 likewise is dimeric in the solid state, but exhibits a 6-membered N–Al–N heterocyclic ring.