A touch of lavender: gas-phase structure and dynamics of the monoterpene linalool validated by microwave spectroscopy

Abstract

The microwave spectrum of linalool, an acyclic monoterpene, was recorded for the first time in the range from 9 to 16 GHz. The only conformer observed under molecular beam conditions was assigned. Fitting the rotational spectrum with two different programs treating internal rotation yielded the rotational constants A = 1.64674020(46) GHz, B = 0.68219862(16) GHz, C = 0.61875100(20) GHz, and the centrifugal distortion constants. The standard deviation of the fit was close to experimental accuracy. A–E splittings due to the internal rotation of one methyl group could be resolved and the internal rotation barrier was determined to be 400.20(64) cm⁻¹. The results from microwave spectroscopy were used to validate the molecular geometry obtained from quantum chemical calculations.