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The rotational spectra of two isotopologues of the 1:1 complex formed between acetone and ethanol have been recorded and analyzed by using Fourier-transform microwave spectroscopy. One rotamer was detected, in which ethanol adopts the gauche form. The two subunits are linked by a conventional O−H⋅⋅⋅O and a weak C−H⋅⋅⋅O hydrogen bond, forming a six-membered ring. Each rotational transition is split into five component lines due to the internal rotations of two nonequivalent acetone methyl groups. The V3 barriers to internal rotation of the two CH3 tops of acetone were determined to be 252(4) and 220(1) cm−1, which are noticeably lower than the value for the monomer (266 cm−1). [ABSTRACT FROM AUTHOR]

The structural and energetic features of the CH⋅⋅⋅π interaction and the internal dynamics of the CHF3 group change drastically in going from benzeneCHF3 to indanCHF3, according to the analysis of the rotational spectrum of the latter complex generated in a supersonic expansion. [ABSTRACT FROM AUTHOR]

The rotational spectra of five conformers of 13- butandiol have been measured by pulsed jet Fourier transform microwave spectroscopy. All of them are stabilized by an internal hydrogen bond and all of them have a GG' or a G'G arrangement of the two hydroxyl oxygens, which means that both oxygen atoms are on the same side with respect to the C1C2C3 plane. Apart from the spectroscopic constants, the relative abundances in the supersonic expansion are provided. [ABSTRACT FROM AUTHOR]

The rotational spectra of five isotopologues of the molecular adduct 1,1,1-trifluoroacetone--water have been assigned using pulsed-jet Fourier-transform microwave spectroscopy. All rotational transitions appear as doublets, due to the internal rotation of the methyl group. Analysis of the tunneling splittings allows one to determine accurately the height of the 3-fold barrier to internal rotation of the methyl group and its orientation, leading to V3 = 3.29 kJ ⋅mol-1 Z (a,i) = 67.5molorespectively. The water molecule is linked to the keton molecule on the side of the methyl group through a O--H- …O hydrogen bond and a C-H* …O intermolecular contact, lying in the effective plane of symmetry of the complex. [ABSTRACT FROM AUTHOR]

We recorded the rotational spectra of six isotopologues of the most stable conformer of 1,2-butanediol in the 59.6–74.4 GHz frequency region. The observed species are the four monosubstituted 13C, the OD···OH and the OD···OD, and the measurements were performed using a Free-Jet Absorption Millimeter Wave spectrometer. The analysis of the 18 experimental rotational constants determined for all the isotopologues together with those of the parent species, lead to the determination of the coordinates in the principal axis system for the substituted atoms. From the theoretical structure, calculated at the B3LYP-D3/aug-cc-pVTZ level of theory, a refinement of the structural parameters led to a partial r 0 geometry, which reproduced all the rotational constants within 1.3 MHz. Image 104309 • The rotational spectra of six isotopologues of the most stable conformer of 1,2-butanediol were measured. • The analysis of the experimental rotational constants lead to the determination of the partial r s and r 0 structures. • NCI analysis shows that the structure is stabilized by hydrogen bonds. [ABSTRACT FROM AUTHOR]