Vibrational Spectrum and Electronic Structure of the [B11H11]2–Dianion

Abstract

AbstractThe vibrational spectrum, geometrical structure and electron‐density distribution (EDD) of the formallycloso(2n+2)‐electron cluster species [B11H11]2–have been studied. The presence of two low‐frequency vibrational modes is evidence of cluster nonrigidity. A rationale for this lies in the results of EDD calculations which show that the polyhedron lacks two‐centre edge‐localized B–B bonds of the 6k–5ktype and that its surface exhibits two six‐membered rings with low electron density. Thus, the polyhedron does not consist of deltahedral faces only and therefore does not have a genuineclosostructure. The data obtained also allow further elucidation of the “diamond‐square‐diamond” mechanism as commonly applied to the fluxionality of [B11H11]2–in solution.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)