A high-resolution microwave study of the butan-2-ol argon complex

The rotational spectrum of a weakly bound complex formed between the chiral secondary alcohol butan-2-ol and the rare gas argon has been observed using Fourier transform microwave spectroscopy. In the complex the butan-2-ol molecule adopts the ga or straight-chain conformation with the hydroxyl hydrogen opposite to the ethyl group. The argon is bonded to the hydroxyl hydrogen, and the H-Ar separation is calculated to be 2.97 Angstrom. Our assignment is aided by a series of calculations performed using the GAUSSIAN 94 ab initio package. The agreement between experimental and calculated values for the rotational constants is good. It has also proved possible to extract quartic centrifugal distortion coefficients using the Watson A-reduction of the rotational Hamiltonian. (C) 2002 Elsevier Science (USA).