Evidence for a photoinduced isonitrosyl isomer in ruthenium dinitrosyl compounds

Abstract

Since the seminal characterisation of two photoinduced linkage isomers (PLIs) in crystals of sodium nitroprusside dihydrate Na₂[Fe(CN)₅(NO)]·2H₂O by photocrystallography, this phenomenon has been described in a large variety of molecular mononitrosyl complexes. The two photoinduced metastable isomers consist of a κO, isonitrosyl, binding mode (MS1) and a κ²N,O, side-on, binding mode (MS2). We have recently detected by infrared spectroscopy various PLI states in dinitrosyl ruthenium complexes, for which only κN binding modes were characterised by photocrystallography. We provide here experimental evidence for a photoinduced isonitrosyl isomer in the [Ru(PCy₃)₂(NO)₂Cl]BF₄ (Cy = cyclohexyl) complex salt, the results being strongly supported by DFT calculations.