Evidence for a photoinduced isonitrosyl isomer in ruthenium dinitrosyl compounds

Since the seminal characterisation of two photoinduced linkage isomers (PLIs) in crystals of sodium nitroprusside dihydrate Na2ijFeIJCN)5IJNO)]·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 [RuIJPCy3)2IJNO)2Cl]BF4 (Cy = cyclohexyl) complex salt, the results being strongly supported by DFT calculations.