Structure and Bonding in Bissilylated Arenium Ions†

The aryl-bridged disilyl cations 8 with an 1,8-naphthalenediyl backbone were synthesized and were identified by NMR spectroscopy. In addition the [B(C6F5)4]- salt of the tolyl-bridged cation 8b was characterized by X-ray crystallography. The NMR spectroscopic and the structural data indicate the arenium ion nature of disilyl cations 8. Results of quantum mechanical computations corroborate the experimental findings, and a Bader-type topological analysis of the electron density in model cation 6 gives a refined picture of the bonding in aryl-bridged disilyl cations 6 and 8.