Ruthenium monoterpyridine complexes with 2,6-bis(benzoxazol-2-yl)pyridine as an ancillary ligand: Synthesis, structure and spectral studies

Ruthenium monoterpyridine complexes, [1]+ and [2]2+, with 2,6-bis(benzoxazol-2-yl)pyridine as an ancillary ligand, L, have been synthesized and characterized by UV–Vis, FT-IR and 1H NMR spectroscopic techniques. The formulations of the complexes were confirmed by the single crystal structure of their perchlorate salts. In both complexes, the RuII center is hexa-coordinated in a distorted geometry. In complex [1]+, the ancillary ligand L behaves as a bidentate ligand; in [2]2+, however, it binds the metal center as a tridentate ligand. The central pyridine nitrogen of terpyridine (Np,trpy) is in a cis position with respect to the central pyridine nitrogen of the ancillary ligand (Np,benz) in complex [1]+ and in a trans-position in complex [2]2+. The cis orientation of Np,trpy and Np,benz in complex [1]+ forces L to behave as bidentate. The quasi-reversible RuII/RuIII couple appears at 0.90 and 1.44 V versus SCE in the case of complex [1]+ and [2]2+, respectively. [1]+, in the presence of aqueous AgNO3, affords [2]2+ through an intramolecular dissociative interchange pathway.

In the ruthenium monoterpyridine complexes [1]+ and [2]2+, the tridentate ancillary ligand L behaves as a bidentate and a tridentate ligand, respectively. Complex [1]+, in the presence of aqueous AgNO3, affords [2]2+ through an intramolecular dissociative interchange pathway.Figure optionsDownload as PowerPoint slide