Tuning Structure and Photoinduced Linkage Isomerism of Tetrapyridine Nitrosyl Ruthenium(II) Complexes by Changing of the trans-to-NO Coordinated Ligand
The perchlorate series of nitrosyl ruthenium tetrapyridine-cations trans-[RuNOPy4X]n+ (where X = OH, Cl, and H2O) were synthesized. The exchange of the anion in excess of sodium perchlorate results in the formation of the hydroxo complex with perchlorate as a counter-anion. The protonation of the coordinated hydroxyl resulted in the formation of the aqua complex in the acidic media. The outcome of the protonation depends on the choice of the acid. Usage of non-coordinating perchloric acids leads to the aqua complex as the product. The ruthenium nitrosyl complex with coordinated chloride anion was a result of interaction of the hydroxo complex with concentrated hydrochloric acid. The crystal structures were determined by X-ray single crystal analysis. The 445-nm irradiation promotes electron transfer from the metal orbital to the antibonding orbital of the nitrosyl group. In the solid phase, this metal-to-ligand charge transfer results in the formation of the metastable states with Ru-ON coordination. These photoinduced linkage isomers for each complex were monitored in IR-spectra and their stability were measured by temperature sweep method described earlier.