A Pericyclic Reaction in the Gas Phase Identified by Rotational Spectroscopy: Reaction of a Thiocarboxylic Acid with Sulfur Trioxide.

The reaction of sulfur trioxide (SO) and thiobenzoic acid (CHCOSH) is investigated in the gas phase under supersonic jet conditions. Rotational spectroscopy of the parent and several isotopically substituted derivatives, in conjunction with DFT calculations at the M06-2X/6-311++G(3df,3pd) level of theory, identify the product as thiobenzoic sulfuric anhydride, CHC(=S)OSOOH. Single point CCSD(T)/CBS(D-T)//M06-2X/6-311++G(3df,3pd) calculations place the electronic energy of the product anhydride 114 kJ/mol lower than that of SO+CHCOSH at infinite separation.

The Microwave Rotational Electric Resonance (RER) Spectrum of Benzothiazole.

The microwave spectra of benzothiazole were measured in the frequency range 2-26.5 GHz using a pulsed molecular jet Fourier transform microwave spectrometer. Hyperfine splittings arising from the quadrupole coupling of the N nucleus were fully resolved and analyzed simultaneously with the rotational frequencies.

Discovery of a Missing Link: First Observation of the HONO-Water Complex.

The still unexplained daytime HONO concentration in the Earth's atmosphere and the impact of water on the HONO chemistry have been a mystery for decades. Several pathways and many modeling methods have failed to reproduce the atmospheric measurements. We reveal in this study the first spectroscopic observation and characterization of the complex of HONO with water observed through its rotational signature.

The effects of proton tunneling, N quadrupole coupling, and methyl internal rotations in the microwave spectrum of ethyl methyl amine.

The spectra of N-ethyl methyl amine, CH(NH)CHCH, were measured using a molecular jet Fourier transform microwave spectrometer in the frequency range of 2 GHz-26.5 GHz. Splittings due to proton inversion tunneling, Coriolis coupling, N quadrupole coupling, and methyl internal rotation were fully resolved.