Triphenylgermyl-lithium in diethyl ether/THF did not react with Al2Me6 to form [(Ph3Ge)AlMe3]- Li(THF)n. Addition of TMEDA to this solution yielded crystalline Ph3GeLi(THF)TMEDA. The reaction of Ph3GeLi in diethyl ether/hexane solution with H3Al-NMe3 in diethyl ether/THF generated [Ph3GeAlH3]Li(THF)4 while the reaction with Me2AlCl led to Ph3GeAlMe2(OEt2) and the trigermyl-aluminate [(Ph3Ge)3AlMe]Li. The analogous aluminate [(Ph3Ge)3AlH]Li(THF)3 was obtained by reacting LiGePh3 with AlH2Cl(OEt2) in the presence of THF. It was expected that the bulky bis(tetramethylpiperidino)chloroalane would react with Ph3GeLi to give the germyl-alane tmp2AlGePh3 which was observed when only diethyl ether was used as a solvent, but in an Et2O/toluene mixture only Ph8Ge3 could be isolated. Increasing the steric requirement of the germyllithium compound by using the bulky (tBu3Si)Me2Ge group instead of the Ph3Ge group led to a straightforward reaction generating the first structurally characterized germyl-alane (tBu3Si)Me2Ge- Al(tmp)2 with a planar tri-coordinated Al center. The X-ray structure determinations showed that the germyl-aluminates have shorter Ge-Al bonds than the germyl-alane inspite of the lower coordination number
The reactions of bis(2,2,6,6-tetramethylpiperidino)aluminum bromide (tmp2AlBr) with Me3SiN3 or Me3SiCN lead to trimeric tmp2AlN3 and tmp2AlCN, respectively, while the reaction with Me3SiOCN produces the bicyclic compound [tmpCON(SiMe3)2]2′ , 3. Similarly, di(tertbutyl) aluminum bromide reacts with Me3SiCN to give tetrameric (Me3C)2AlCN, 4. The compounds (Me3C)2AlN3 and (Me3C)2AlOCN, obtained as oily products, have tetracoordinated Al atoms as shown by NMR spectroscopy, but the degree of oligomerization has not been determined.