Gas‐Phase Structure of N,N‐Dimethylglycine

Abstract

Three conformers of the neutral amino acid N,N-dimethylglycine [(CH3)2NCH2COOH] were detected in a supersonic expansion by a combination of laser ablation (LA) and molecular-beam Fourier transform microwave (MB-FTMW) spectroscopy. A bifurcated methyl-to-carbonyl (C--HO==C) weak intramolecular hydrogen bond might stabilise the most stable conformer of C(s) symmetry. The second most stable conformer of C1 symmetry has a hydrogen bond between the hydroxyl group and the lone pair at the nitrogen atom (NH--O). The r(s) and r0 structures were derived for this conformer from the rotational data for the parent and six minor 13C, 15N and OD isotopomers. A third conformer exhibits a cis-carboxyl functional group and C1 symmetry. Ab initio MP2/6-311++G(d,p) predictions of the spectroscopic parameters were useful in analysing the spectra. In particular, the agreement of the nuclear quadrupole coupling constants with those calculated was conclusive in identifying the different conformers.