Fragmentation of the intramolecularly coordinated alane Me2NCH2CD2CH2AlBr2:: A matrix-isolation study

The selectively deuterated aluminum bromide Me2NCH2CD2CH2AlBr2 was prepared from AlBr3 and Li[CH2CD2CH2NMe2] and analyzed by NMR, mass spectrometry, and elemental analysis. High-vacuum thermolyses of this intramolecularly coordinated precursor were investigated with matrix-isolation techniques. Among other products, the known hydride HAlBr2 was identified by IR spectroscopy in argon matrices. In none of the thermolysis experiments the deuteride DAlBr2 was found. The predicted vibrational frequencies of DAlBr2 are discussed. These findings reveal that a beta-hydrogen elimination can be excluded as a fragmentation path. They are interpreted as resulting from a homolysis of the Al-C bond of the starting compound.