Isolation of ruthenium compounds with bidentate benz(imidazole/othiazole) chelators

Herein, we report the isolation of ruthenium(II/III) compounds with N,O-donor heterocyclic ligands. The 1:2 molar ratio reactions of trans-[RuCl2(PPh3)(3)] with 2-hydroxyphenylbenzimidazole (Hobz) and 2-hydroxyphenylbenzothiazole (Hobs), respectively, led to the formation of the diamagnetic ruthenium(II) complex salt, [RuCl(Hobz)(2)(PPh3)]Cl(1) and the paramagnetic ruthenium complex, [(RuCl)-Cl-III(obs)(2)(PPh3)](2). The X-ray crystal structures of both metal complexes show a distorted octahedral geometry imposed by the '2 + 2' coordination modes of their chelators. The ruthenium compounds 1 and 2 were also characterized via physico-chemical and spectroscopic methods. In addition, the redox properties were probed using cyclic voltammetry and the presence of the paramagnetic metal centre of compound 2 was confirmed by low and room temperature electronic paramagnetic resonance spectroscopy in the liquid and solid states. Furthermore, density functional theory studies indicated that the complex cation of 1 was more energetically favourable than that of the neutral complex 2.