The 1:1 benzofuran–formaldehyde complex has been chosen as model system for analyzing π→π* interactions in supramolecular organizations involving heteroaromatic rings and carbonyl groups. A joint “rotational spectroscopy–quantum chemistry” strategy unveiled the dominant role of π→π* interactions in tuning the intermolecular interactions of such adduct. The exploration of the intermolecular potential energy surface led to the identification of 14 low‐energy minima, with 4 stacked isomers being more stable than those linked by hydrogen bond or lone‐pair→π interactions. All energy minima are separated by loose transition states, thus suggesting an effective relaxation to the global minimum under the experimental conditions. This expectation has been confirmed by the experimental detection of only one species, which was unambiguously assigned owing to the computation of accurate spectroscopic parameters and the characterization of 11 isotopologues. The large number of isotopic species opened the way to the determination of the first semi‐experimental equilibrium structure for a molecular complex of such a dimension.

The internal rotation of methyl groups and nuclear quadrupole moments of the halogens Cl, Br, I in o-halotoluenes result in complex spectral fine and hyperfine structures in rotational spectra which can be related to qualitative concepts in chemistry.

Phenylmethanimine is an aromatic imine with a twofoldr elevancei nc hemistry:o rganic synthesis and astrochemistry.T ot ackle both aspects, am ultidisciplinary strategy has been exploited and anew,easily accessible synthetic approach to generate stable imine-intermediates in the gas phase and in solution has been introduced. The combination of this formation pathway, basedo nt he thermal decomposition of hydrobenzamide, with as tate-of-the-artc omputational characterization of phenylmethaniminel aidt he foun-dationfor its first laboratory observation by means of rotationale lectric resonance spectroscopy.B oth E and Z isomers have been accurately characterized, thus providing ar eliable basis to guide futurea stronomical observations. Af urther characterization has been carried out by nuclear magnetic resonance spectroscopy,s howingt he feasibility of this synthetica pproach in solution. The temperature dependence as well as possible mechanismsofthe thermolysis processh ave been examined.

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first reported high resolution microwave spectrum of acetone cyanohydrin• first characterization regarding Coriolis and hyperfine structure• revealing complexity due to large amplitude motions