title: Microwave spectra and structures of 1,2-(ortho)- and 1,7-(meta)-carborane, C2B10H12.
abstract: The microwave spectra of 1,2- and 1,7-dicarba-closo-dodecaborane(12), C(2)B(10)H(12) (ortho- and meta-carborane), have been recorded for the first time at room temperature in the 32-88 and 24-80 GHz spectral ranges, respectively. The spectra of the parent species (1,2-C(2)(11)B(10)H(12) and 1,7-C(2)(11)B(10)H(12)) have been assigned, together with those of four monosubstituted ((10)B) 1,2-C(2)(10)B(11)B(9)H(12) and 1,7-C(2)(10)B(11)B(9)H(12) isotopologues. The microwave spectra confirm that the structures of each of these two molecules are slightly distorted icosahedrons of C(2v) symmetry. A previous determination of the gaseous structures of these two carboranes by the gas electron-diffraction method was based on several assumptions about the B-B bond length differences. All B-B bond lengths have now been redetermined using the substitution (r(s)) method, which is independent of such restraints. Although several of the r(s) and electron-diffraction bond lengths are in good agreement, there are also differences of up to 0.026 Å. Quantum chemical calculations at the B3LYP/6-311++G(3df,3pd) level of theory have also been performed.
authors: Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Oslo, Oslo, Norway.
authors: Svein
authors: S
authors: Samdal
authors: Harald
authors: H
authors: Møllendal
authors: Drahomir
authors: D
authors: Hnyk
authors: Josef
authors: J
authors: Holub