Competition for Hydride Between Silicon and Boron: Synthesis and Characterization of a Hydroborane-Stabilized Silylium Ion.

Abstract

Potent main‐group Lewis acids are capable of activating element‐hydrogen bonds. To probe the rivalry for hydride between silylium‐ and borenium‐ion centers, a neutral precursor with the hydrosilane and hydroborane units in close proximity on a naphthalene‐1,8‐diyl platform was designed. ion of one hydride leads to a hydroborane‐stabilized silylium ion rather than a hydrosilane‐coordinated borenium ion paired with [B(C6F5)4]− or [HCB11Cl11]− as counteranions. Characterization by multinuclear NMR spectroscopy and X‐ray diffraction supported by DFT calculations reveals a cationic, unsymmetrical open three‐center, two‐electron (3c2e) Si−H−B linkage.