Thermal conversion of closo-1,2-(SiMe3)(2)-1,2-C2B4H4 to closo-1,6-(SiMe3)(2)-1,6-C2B4H4: Structure determination by ab initio calculations, gas-phase electron diffraction, and low-temperature x-ray diffraction

closo-1,2-(SiMe3)(2)-1,2-C2B4H4 undergoes thermal conversion to 1,6-(SiMe3)(2)-1,6-C2B4H4. The reaction pathway was monitored by B-11 NMR spectroscopy. The structures of the 1,2- and 1,6-isomers were optimized at the HF/6-31 G* ab initio level. Gas-phase electron diffraction studies for both isomers are reported, as well as low-temperature X-ray crystal structure determinations. Comparison of calculated structural data with the data obtained experimentally shows good agreement between theory and experiment.