Matrix reactivity of AlF and AlCl in the presence of HCl and HBr: generation and characterization of the new Al(III) hydrides HAlFCl,HAlFBr, and HAlClBr and the monomeric mixed Al(III) halides AlX(2)Y (X,Y = F,Cl, or Br)

The spontaneous and photolytically induced reactions of AlF and AlCl in the presence of HCl and HBr in solid argon matrices were followed and the products identified and characterized by means of IR spectroscopy. Quantum mechanical calculations allow for a further evaluation of the properties of the reaction products. These are the adducts AlF.HCl, AlF.HBr, and AlCl.HBr, representing the products of spontaneous reactions, and the trivalent Al(III) hydrides HAlFCl, HAlFBr, and HAlClBr, which were formed upon photoactivation of these complexes. All three hydrides are planar molecules (C(s)() symmetry) with bond angles in agreement with the predictions of the VSEPR theory. In addition, the mixed halides AlFCl(2), AlFBr(2), and AlClBr(2) were formed upon photolysis. The bisadducts AlF.(HCl)(2) and AlF.(HBr)(2) are likely to be the precursors to these species.