N, O and F K-edges XAS and DFT combination for the exploration of linkage isomers of coordinated nitric oxide in a ruthenium nitrosyl complex

We report on the experimental investigation of single crystals of trans-[RuNOPy₄F](ClO₄)₂ (1) in its ground state (GS). The X-ray absorption spectroscopy (XAS) spectra measured at the N, O and F K-edges were compared to TDDFT calculations to identify and assign the absorption peaks, and to elucidate the structures of coordinated nitric oxide (NO). Based on a reasonable match of experimental and calculated spectra of GS, the N, O and F K-edges XAS spectra of Ru-ON (MS1) and Ru-η²-(NO) (MS2) isomers of 1 were calculated. According to the calculations, the energy or/and intensity of the 1 s→LUMO, LUMO+ 1 peaks of N, O or F K-edge changes significantly after GS isomerization to both MS1 and MS2. Current theoretical modeling of the NO linkage isomer in 1 is a background for the future investigation of isomerization process of NO by XAS methods. Since the investigated isomerization occurs in a variety of different nitrosyl complexes, obtained results can be extrapolated to a large family of transition metal nitrosyl compounds.