Hypervalent Carbon Atom: 'Freezing' the S_N2 Transition State

摘要

The quest for hypervalent molecules, in particular ones involving pentavalent carbon atoms, has challenged chemists for about a century. Over the decades, the non-hypervalence (e.g., A; r_1 and r_2 are bond distances) or hypervalence (e.g., B) of various atoms in both molecular as well as extended structures has been investigated. Recently, we have addressed the issue of why silicon is hypervalent (i.e., pentavalent) in [Cl-SiH3-Cl]~-, whereas the carbon atom in [Cl-CH3-Cl]~-is not.