A Unique Transition Metal-Stabilized Silicon Cation

作者：Muether Kristine; Froehlich Roland; Mueck Lichtenfeld Christian; Grimme Stefan; Oestreich Martin^*

来源：Journal of the American Chemical Society, 2011, 133(32): 12442-12444.

DOI：10.1021/ja205538t

Trivalent silicon cations are exceptionally strong electron pair acceptors that react, either desired or undesired, with almost any sigma and pi basic molecule. One way of intramolecular attenuation of the Lewis acidity of these superelectrophiles is by installation of a ferrocene unit at the electron-deficient silicon atom. While well-understood for isoelectronic alpha-ferrocenyl-substituted carbenium ions and also boranes, the stabilizing interactions between the ferrocene backbone and a positively charged silicon atom are not clear due to the challenge of crystallizing such cations. The structural characterization of our ferrocene-stabilized silicon cation now reveals an unprecedented bonding motif different from its analogues. An extreme dip angle of the silicon atom toward the iron atom is explained by two three-center-two-electron (3c2e) bonds through participation of both the upper and the lower aromatic rings of the ferrocene sandwich structure. The positive charge is still localized at the silicon atom that also retains a quasi-planar configuration.

• 出版日期2011-8-17