The synthesis of a novel divalent silicon compound by debromination of the corresponding dibromosilyl precursor is reported. The silylene possesses a unique reactivity toward electrophiles of the type R-X (R = H, silyl; X = halogen, triflate) in comparison with the germanium congener. DFT calculations suggest that this is due to a much higher basicity of the silylene versus that of germylene lone-pair electrons. Thus, addition of Me3SiX to the silylene (X = OSO2CF3, triflate) furnishes the corresponding (kinetically favored) 1,4-adduct which subsequently rearranges to the thermodynamically favored 1,1-adduct.

No abstract

By employing the chelate dicarbene 1, the new chlorogermyliumylidene complex 2 could be synthesized and isolated in 95% yield. Dechlorination of 2 with sodium naphthalenide furnishes the unique cyclic germadicarbene 3 which could be isolated in 45% yield. Compound 3 is the first isolable Ge(0) complex with a single germanium atom stabilized by a dicarbene. Its molecular structure is in accordance with DFT calculations which underline the peculiar electronic structure of 3 with two lone pairs of electrons at the Ge atom.

An electronic chameleon: The planar cyclogermylene 1 can be described by the resonance structures 1 A and 1 B. It is accessible in 79 % yield by dehydrohalogenation of the corresponding (β‐diketiminato)chlorogermylene by LiN(SiMe3)2. Although the contribution of the dipolar resonance structure 1 A is relatively small, its influence is seen in the transformations of 1 with Me3SiOTf or 1,2‐dibromoethane. R=2,6‐diisopropylphenyl.