Thermolyse von intramolekular koordinierten Alanen mit dem 3-(Dimethylamino)propyl-Liganden : eine Matrixisolationsstudie

The high vacuum thermolyses of a number of Alanes equipped with one 3-(dimethylamino)propyl-ligand and two halides (Pr'AlX2; Pr' = (CH2)3N(CH3)2, X = Cl, Br) or two of the mentioned organic ligands and one halide or azido substituent respectively (Pr'2AlX; Pr' = (CH2)3N(CH3)2, X = Br, N3) were investigated by the matrixisolation technique in combination with IR-spectroscopy. The resulting products were identified with the help of literature data and with calculated vibrational spectras based on ab-initio-calculations. Monomeric HAlX2 (X = Cl, Br) showed to be the main inorganic product in the thermolysis of all mentioned intramolecularly coordinated halide containing alanes. In the experiments with the double intramolecularly coordinated bromoalane (Pr'2AlBr) monomeric H2AlBr proved to be an important inorganic product as well. Apart from AlH3 and HAlCl2, HAlBr2 and H2AlBr are so far the only known monomeric alanes without sterically demanding substituents. The composition of the organic and inorganic products indicates that the braking of the AlC-bond initiates the thermolysis process. This interpretation found further support in an isotopic labelling experiment, in which the beta position of the ligand was deuterated. The experiments proved that the ligand is not separated in a beta elimination reaction as proposed in earlier publications. The thermolysis of the potential single-source-precursor for III/V-semiconductors in CVD-processes, the double intramolecularly coordinated azidoalane, is not understood yet, mainly due to the lack of detection of any inorganic compound