Isomers of NCO2: IR-absorption spectra of ONCO in solid Ne

Photolytic insertion of carbon monoxide into nitrosyl chloride: formation of nitrosoformyl chloride

Nitrosocarbonyls are exotic intermediates that remain scarcely characterized. By UV photolysis (365 nm) of nitrosyl chloride (ClNO) embedded in solid CO ice at 20 K, the elusive nitrosoformyl chloride (ClC(O)NO) has been synthesized via CO-insertion into the Cl-N bond in ClNO. The characterization of ClC(O)NO with matrix-isolation IR spectroscopy is supported by ¹³C and ¹⁵N isotope labeling and quantum chemical calculations at the B3LYP/6-311+G(3df) level of theory. Upon subsequent laser irradiation at 266 nm, CO-elimination in ClC(O)NO occurs by reformation of ClNO. In line with the calculated potential energy surface for ClC(O)NO at the CCSD(T)-F12a/aug-cc-pVTZ//B3LYP/6-311+G(3df) level, the observed IR frequencies and the corresponding isotopic shifts coincide with the calculated values for the lowest-energy planar conformer, in which the CO and NO moities adopt trans configuration with respect to the C-N bond. Furthermore, the CO-insertion in ClNO involves a stepwise pathway by first homolytic cleavage of the Cl-N bond in ClNO (→ Cl˙ + ˙NO), followed by successive CO-trapping (CO + Cl˙ → ClCO˙) and radical combination (ClCO˙ + ˙NO → ClC(O)NO) inside the solid CO-matrix cages.

Theoretical Characterization of the Structure and Spectroscopy of HCNO2 Isomers and Applications

We carried out a theoretical, fully ab initio, investigation of the stable forms of the [H,C,N,O,O] pentatomic molecular system, whose isomers are involved in fundamental combustion and atmospheric processes and are of potential interest for astrophysics. By adopting the MP2 and CCSD(T) electronic structure methods, combined with extrapolations to the complete basis set (CBS) limit, we characterized 20 low-energy isomers, excluding weak van der Waals complexes. For these molecules, we determined a set of geometrical parameters, relative energies, anharmonic vibrational frequencies, IR intensities, and fragmentation/formation energies from various atomic and/or molecular fragments. We discuss the relevance of the present findings for the search of new molecular species in astrophysical and atmospheric media and give suggestions for their possible detection in laboratory experiments. The set of data provided by the present work should facilitate the identification of these species from their gas-phase and low-temperature solid matrix spectra, whenever measured.

The hypothiocyanite radical OSCN and its isomers

An elusive biologically relevant hypothiocyanite radical (OSCN) has been generated in the gas phase, and its reversible photoisomerization with two novel isomers OSNC and SOCN has been observed in cryogenic Ar and N₂ matrices at 2.8 K.

Global picture of isomerization and dissociation of CN2O2: new metastable isomers

A comprehensive potential energy surface of CN₂O₂, covering 15 new isomers and 30 new transition states was constructed to predict three new observable isomers 14, 22 and 29.