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Methyl Torsional State Analysis of the Jet-Cooled Microwave Spectrum of N-Acetylglycine



Francis J. Lovas, R J. Lavrich, David F. Plusquellic


The microwave spectrum of N-acetylglycine was obtained using a NIST Fourier-transform microwave spectrometer equipped with a heated, pulsed-nozzle source. One conformer has been identified and its spectrum assigned. The conformer has CS point group symmetry and an intra-molecular hydrogen bond between the carbonyl and amide groups of the 5-membered glycine unit. Internal rotation of the methyl rotor group leads to splitting of the rotational lines into A and E symmetry tunneling states. The 14N nuclear-quadrupole hyperfine structure verifies the rotational and internal-rotor state assignments. The values for the angle between the methyl rotor axis and the inertial axes and for the V3 barrier of 57.5(1) cm 1 are in best agreement with the calculated values for the lowest energy conformer of the four conformers predicted at the MP2/6-311++G(d,p) level of theory.
Journal of Molecular Spectroscopy


ab initio calculation, internal rotation, microwave spectrum, molecular structure, N-acetylglycine, nuclear quadrupole splitting, rotational spectrum


Lovas, F. , Lavrich, R. and Plusquellic, D. (2004), Methyl Torsional State Analysis of the Jet-Cooled Microwave Spectrum of N-Acetylglycine, Journal of Molecular Spectroscopy (Accessed December 7, 2023)
Created May 1, 2004, Updated February 17, 2017