Linking deltahedral Zintl clusters with conjugated organic building blocks: synthesis and characterization of the Zintl triad [R-Ge9-CH=CH-CH=CH-Ge9-R]4-.

The accessibility of triads with deltahedral Zintl clusters in analogy to fullerene-linker-fullerene triads is another example for the close relationship between fullerenes and Zintl clusters. The compound {[K(2.2.2-crypt)]4[RGe9-CH=CH-CH=CH-Ge9R]}(toluene)2 (R=(2Z,4E)-7-amino-5-aza-hepta-2,4-dien-2-yl), containing two deltahedral [Ge9] clusters linked by a conjugated (1Z,3Z)-buta-1,3-dien-1,4-diyl bridge, was synthesized through the reaction of 1,4-bis(trimethylsilyl)butadiyne with K4Ge9 in ethylenediamine and crystallized after the addition of 2.2.2-cryptand and toluene. The compound was characterized by single-crystal structure analysis as well asNMR and IR spectroscopy.