Molecular pyrophoric compound

The carbaalanes [8, 9] possess clusters formed by aluminum and carbon atoms. They represent a new class of compounds which, in some respects, may be compared to the important class of carbaboranes. Usually, they were obtained by the reaction of aluminum alkynides with aluminum hydrides (hydroalumination) and the release of trialkylaluminum derivatives (condensation). The first carbaalane, (AlMe)g(CCH2Ph)5H 3 [10], was synthesized by the treatment of dimethylalumi-num phenylethynide with neat dimethylaluminum hydride. The idealized stoichiometric ratio of the components is given in Eq. (2), which also shows a schematic drawing of the molecular structure. Compound 3 was isolated in the form of colorless crystals in 60% yield. While 3 is only slightly air-sensitive, the less sterically shielded propynide derivative 4, also shown in Eq. (2), is highly pyrophoric [11],... 

The synthesis of the first molecular Zn-Zn-bonded compound, however, was not achieved until 2004. Carmonas discovery of dizincocene Cp ZnZnCp (4, Cp = CgMe ) by reaction of Cp 2Zn and EtjZn is shown in Scheme 12.4 [21]. The pyrophoric compound 4 is unstable when exposed to oxygen and moisture and is soluble in common organic solvents. It could be stored at room temperature under inert atmosphere indefinitely and undergoes sublimation in high vacuum at 70 °C without significant decomposition. The crystal structure shows that the Zn-Zn distance is very short... 

Ce(acac)3 may be used instead of isopropoxide, but in this case the obtained product is less pure. The cerium complex is crystallized from the reaction mixture as black needles. The compound is pyrophoric and slowly decomposed by deaerated water. Its structure has been confirmed by the data of elemental analysis, IR-, NMR and mass spectrometry (the molecular ion is present in the spectrum) and the preliminary X-ray data. 

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