Nitrosyl linkage photoisomerization in heteroleptic fluoride ruthenium complexes derived from labile nitrate precursors

Abstract

Four complexes with trans-ON–Ru–F coordinate were synthesized from the corresponding nitrate precursors. The treatment of fac-[RuNO(NH₃)₂(NO₃)₃] with hydrofluoric acid results in the substitution of the labile nitrate ligands by H₂O and F⁻, whereas the treatment of trans-(NO,NO₃)-cis-(NH₃,NH₃)-[RuNO(NH₃)₂Py₂(NO₃)](NO₃)₂·H₂O leads to additional pyridine ligand elimination. The structures of the four complexes were characterized by X-ray diffraction: trans(NO,F)-cis(NH₃,NH₃)-[RuNO(NH₃)₂(H₂O)₂F]SiF₆ (I), trans(NO,F)-cis(NH₃,NH₃)-[RuNO(NH₃)₂Py(NO₃)F]₂SiF₆·H₂O (II), trans(NO,F)-cis(NH₃,NH₃)-[RuNO(NH₃)₂Py(H₂O)F](ClO₄)₂ (III) and trans(NO,F)-cis(NH₃,NH₃)-[(RuNOPy(NH₃)₂F)₂(μ-O₂H₃)](ClO₄)₃ (IV). Upon light irradiation, complexes I, II and III show reversible formation of metastable linkage isomers MS1 and MS2 with remarkable thermal stability of both isomers. Moreover, complexes I and III show the highest thermal stability of the MS2 isomers, which leads to a higher photogeneration temperature of MS1 via the GS → MS2 → MS1 mechanism. Such excellent properties of the resulting materials can be used in the design of molecular based data storage devices.