Collect. Czech. Chem. Commun. 2010, 75, 1115-1123
Published online 2010-11-09 12:03:53

Revisiting B20H16 by means of a joint computational/experimental NMR approach

Drahomír Hnyka,*, Josef Holuba, Tomáš Jelínekb, Jan Macháčeka and Michael G. S. Londesborougha,*

a Institute of Inorganic Chemistry, Academy of Science of the Czech Republic, v.v.i., 250 68 Husinec-Řež, Czech Republic
b Katchem Ltd., 250 68 Husinec-Řež, Czech Republic


A new synthesis of the fused macropolyhedral boron cluster B20H16 is described and its molecular structure in solution discussed, based on multi-nuclear NMR spectra, including COSY measurements, in relation to its previously elucidated solid-state structure. To verify the conclusions from the NMR study, experimentally determined chemical shifts are compared with calculated values at the GIAO-B3LYP level with a TZP basis set by Huzinaga. There is a very good agreement between the experimental and computed δ(11B) values, suggesting that the MP2/6-31G* internal coordinates are a reasonable representation of the molecular geometry of this twenty-vertex cluster in solution that is essentially the same as its solid-state structure. A computational analysis of the FMO orbitals of B20H16, in particular of the LUMO, reveals that the four naked boron atoms, common for two shared icosahedral subclusters, are the reactive sites of this D2d-symmetrical molecule.

Keywords: Boron; Ab initio calculations; NMR spectroscopy; Clusters.

References: 24 live references.