Generation and spectroscopic identification of NCXNC and NCNCX (X = S, Se) in low-temperature inert matrices

Abstract

Equilibrium structures and relative energies of nine–nine (seven open-chain and two cyclic) isomers of the [2C,2N, X] systems (X=O, S, Se) were determined by the CCSD(T) method. Harmonic and anharmonic vibrational wavenumbers, infrared and Raman intensities, and UV excitation energies were also computed to assist in the spectroscopic identification of these species. The isomers of the [2C, 2N, S] and the [2C, 2N, Se] systems were studied by matrix-isolation IR spectroscopy. First, NCSCN and NCSeCN were prepared and investigated in low-temperature Ar and Kr matrices. Then these species were photolyzed in the matrices at 254nm, which led to the formation of other isomers. Comparing matrix-isolation and computed IR spectra, the previously known NCNCS molecule, and the novel NCSNC, NCSeNC, and NCNCSe species were identified among the photolysis products.