Complexes of Aluminum, Gallium and Indium With Pyrone Derivatives

The reaction of aluminum and gallium trichlorides with 3-hydroxy-2-methyl-4H-pyran-4-one (HMa) in benzene yields M(HMa) 3 CI 3 (M = Al or Ga) adducts, whereas with indium trichloride the ln(HMa) 25 CI 3 complex has been isolated. In analogous conditions the other aluminum trihalides yielded complexes containing the maltolato ion, as AI(HMa) 2 (Ma)Br 2 or AI(Ma) 2 l. Moreover by using the neutral ligand 2,6-dimethyl-4H-pyran-4-one (DMP) the adducts AI(DMP) 2 CI 3 , AI(DMP) 3 X 3 (X = Br or I), GafDMP^ 5 CI 3 and ln(DMP) 2 CI 3 have been obtained. The compounds have been characterized by IR and proton NMR spectroscopy and by thermogravimetric (TG and DTA) analysis. The behaviour of the HMa complexes in deuterated dimethyl sulfoxide is discussed on the basis of proton NMR spectra.