Cationic closo-carboranes 2. Do computed 11B and 13C NMR chemical shifts support their experimental availability?

• Published in: Journal of computational chemistry Vol. 34; no. 8; pp. 656 - 661
• Main Authors: Hnyk, Drahomír, Jayasree, Elambalassery G.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 30.03.2013
• Subjects: 11B NMR; boron clusters; dynamic electron correlation; weakly-coordinating cations
• ISSN: 0192-8651; 1096-987X
• DOI: 10.1002/jcc.23176

11B and 13C NMR spectra of so‐far experimentally unknown carbon‐rich cationic closo‐carboranes C3Bn–3Hn+ (n = 5, 6, 7, 10, 12) have been calculated at the GIAO‐MP2 level and subsequently analyzed to reveal the nature of bonding in these potentially weakly coordinating cations. All previous rules derived for understanding 11B NMR spectra of borane derivatives can be applied to realistically account for the corresponding shieldings. The correlated wavefunction for n = 5 and, to a lesser extent, for n = 10 seems to be decisive when trying to compute realistic shielding tensors, which is in agreement with the corresponding known dicarbaboranes. For other cluster dimensions noncorrelated wavefunctions also work well, in particular in relation to the corresponding dicarbaboranes. All these observations strongly support the fact that experimental availability of these unique clusters is possible. © 2012 Wiley Periodicals, Inc. Computationally predicted closo‐tricarbaboranes C3Bn–3Hn+ (n 5 5, 6, 7, 10, 12) are further analyzed in terms of computing their 11B and 13C chemical shifts. The data obtained for these potentially weakly coordinating cations do not show any substantial deviations from known values of chemical shifts in the area of boron cluster chemistry, and on that basis their experimental availability is possible.