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Viktoria H. Däschlein-Gessner, Chandrajeet Mohapatra, Lennart T. Scharf, Thorsten Scherpf, Bert Mallick, Kai-Stephan Feichtner, Christopher M. Schwarz

• The preparation of the first stable diylide-substituted stannylene and germylene ( \(\bf{Y_{2}E}\), with E=Ge, Sn and Y=PPh\(_{3}\)-C-SO\(_{2}\)Tol]\(^{−}\)) is reported. The synthesis is easily accomplished in one step from the sulfonyl-substituted metalated ylide \(\bf{YNa}\) and the corresponding ECl\(_{2}\) precursors. \(\bf{Y_{2}Ge}\) and \(\bf{Y_{2}Sn}\) exhibit unusual structures in the solid state and in solution, in which the three adjacent lone pairs in the C-E-C linkage are arranged coplanar to each other. As shown by DFT studies, this bonding situation is preferred over the typical π-donation from the ligands into the empty p-orbital at the metal due to the strong anion-stabilizing ability of the sulfonyl groups in the ylide backbone and their additional coordination to the metal. The alignment of the three lone pairs leads to a remarkable boost of the HOMO energy and thus of the donor strengths of the tetrylenes. Hence, \(\bf{Y_{2}Ge}\) and \(\bf{Y_{2}Sn}\) become stronger donors than their diamino or diaryl congeners and comparable to cyclic alkyl(amino)carbenes. First reactivity studies confirm the high reactivity of \(\bf{Y_{2}Ge}\) and \(\bf{Y_{2}Sn}\), which for example undergo an intramolecular C−H activation reaction via metal–ligand cooperation.