Inversion of Bicyclic Decanes: Rotational Spectra of the Trans and Double Cis Conformations of 2-Decalone.

The conformational landscape of the bicyclic molecule 2-decalone has been studied in a jet-cooled expansion by using rotational spectroscopy. The investigation covered the frequency region 7-19 GHz using broadband fast-passage IMPACT Fourier-transform microwave techniques. The introduction of the asymmetric carbonyl substituent in the double-chair decalin skeleton originates two distinct inverting conformers with cis ring junction, which were independently identified and characterized in the gas phase. Additionally, a single trans conformer was detected, as expected for the non-inverting equatorial ring junction. Accurate rotational parameters and quartic centrifugal distortion constants have been determined for the three observed species. A population estimation is given for the observed conformations based on relative intensities. Supporting ab initio calculations up to MP2/cc-pVTZ complement the experimental work.