Gallium-carbon bonds

The trimethylamine adduct of aluminum hydride (alane) has been of recent interest as a precursor for the chemical vapor deposition (CVD) of aluminum metal1 and aluminum gallium arsenide thin films.2 Because of the absence of aluminum-carbon covalent bonds in the precursor, carbon incorporation in the resulting films can be suppressed significantly. In addition, the deposition temperature can be lowered. 

The preparation of semiconductors by thermal decomposition would appear to be impossible because of the high amount of energy required to break all of the metal-carbon bonds before the atomic species could be formed. However, the thermal method is successful because the reaction to form free methyl radicals, which combine to form ethane, lowers the energetic requirements for the formahon of gallium, for example, according to the equation... 

Crystals of complex 112 suitable for an X-ray structure determination were obtained on cooling a solution in pentane to — 30 °C. The structure determined is shown in Fig. 7.9. The most remarkable structural feature of 112 is that the gallium center is connected to the zirconium through two different c-carboxylic bridges. One of them contains the cyclo-C6Hg system, which is t]1-bonded to gallium and r 2-coordinated to zirconium. It is noteworthy that carbon atom C-2 is planar tetracoordinate. It is connected to four neighboring atoms in the c-plane, specifically to carbon atoms C-l and C-3 and to both metal centers [175]. 

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