A New Heteroleptic Complex of Nitrosyl Ruthenium with Ethylenediamine and the NO–Ru–F Trans-Coordinate: Synthesis, Structure, and Photoinduced Linkage Isomerization

A new method is proposed to synthesize ethylenediamine complex [RuNO(en)₂OH]I₂ from K₂[RuNOCl₅], which increases the target product yield to 76%. Subsequent treatment of nitrate salt [RuNO(en)₂ OH](NO₃)₂ with concentrated HF with the precipitation of HClO₄ gives [RuNO(en)₂F](ClO₄)₂ with a quantitative yield. According to the single crystal XRD data, in the [RuNO(en)₂F]²⁺ cationic moiety, nitrosyl and fluoride are in the trans-position relative to each other, and in the ruthenium coordination environment, the equatorial plane is composed of four nitrogen atoms from ethylenediamine ligands. The 450 nm light irradiation of the [RuNO(en)₂F](ClO₄)₂ complex at 80 K results in the formation of metastable linkage isomer MS1 with nitrosyl group coordination through the oxygen atom. According to the IR spectroscopic data, the population of MS1 is about 1%, and the respective vibrational band disappears when heated in a temperature range of 280-310 K. The activation parameters of the MS1–GS (ground state) transition according to the DSC data are E_a = 107.1±6.8 kJ/mol, lnk₀ = 36.1±2.6.