TDDFT-modeling of theoretical UV spectra of binuclear sulfur-containing iron nitrosyl clusters and products of their decomposition

Abstract

The UV spectra of four binuclear sulfur-containing iron nitrosyl clusters, namely, cationic Fe₂{[S(CH₂)₂NH₃]₂(NO)₄}SO₄·2.5H₂0 and Fe₂[(SC₅H₁₁NO₂)₂(NO)₄]SO₄·5H₂O, anionic Na₂[Fe₂(S₂O₃)₂(NO)₄]·4H₂O, and neutral [Fe₂(SC₅H₆)₂(NO)₄], were modeled using time-dependent density functional theory (TDDFT) and compared with experimental results. It was determined that the strong bands at 310 and 360 nm in the experimental spectra correspond to electronic transitions (Fe—NO) → π*(Fe—NO), but the unshared electron pairs of sulfur atoms also contribute. The presence of an aromatic ring in the sulfur-containing ligand changes the form of the UV spectrum, as was observed in the experiment. Strong characteristic bands are absent from the theoretical spectra of possible products.