The M6N6 core in the moelcular structures of these metall-silazane-cages can be described as a bitruncated square bipyramid (tetraasteran-like; see H. M. Hutmacher, H. G. Fritz, H. Mussow, Angew. Chem., 78, 1975, 174). It is formed by four six-membered SiGa2N3-rings in the boat conformation, sharing the three stern-atoms and the three prow-aoms with each nighbour-ring. Thus, two planar four-membered SiGaN2-rings are formed. In all rings metall and nitrogen atoms occupate alternating sites.
The Structures of these type of metal-silazanes are quite similar (fig. 3).
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| fig. 1: Molecular structure of the Ga-silazane [RSi(NH)3GaEtGaEt2]2 |
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| fig 2: Molecular structure of the Al-silazane [RSi(NH)3AlMeAlMe2]2 , 50% thermal elipsoids. |
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| fig 3: Least-squares-fit of the two molecules mentioned above. |
This cages have been synthesized by Carsten
Rennekamp.