Mono and dinuclear arene ruthenium complexes containing 6,7-dimethyl-2,3-di(pyridine-2-yl)quinoxaline as chelating ligand: Synthesis and molecular structure

The mononuclear cations of the general formula [(η⁶-arene)RuCl(dpqMe₂)]⁺ (dpqMe₂ = 6,7-dimethyl-2,3-di(pyridine-2-yl)quinoxaline; arene = C₆H₆, <b>1</b>; C₆H₅Me, <b>2</b>; <i>p</i>-Pr<i>ⁱ</i>C₆H₄Me, <b>3</b>; C₆Me₆, <b>4</b>) as well as the dinuclear dications [(η⁶-arene) ₂Ru₂Cl₂(μ-dpqMe₂)]²⁺ (arene = C₆H₆, <b>5</b>; C₆H₅Me, <b>6</b>; <i>p</i>-Pr<i>ⁱ</i>C₆H₄Me, <b>7</b>; C₆Me₆, <b>8</b>) have been synthesised from 6,7-dimethyl-2,3-di(pyridine-2-yl)quinoxaline (dpqMe₂) and the corresponding chloro complexes [(η⁶-C₆H₆)Ru(μ-Cl)Cl]², [(η⁶-C₆H₅Me)Ru(μ-Cl)Cl]₂, [(η⁶-<i>p</i>-Pr<i>ⁱ</i>C₆H₄Me)Ru(μ-Cl)Cl]₂ and [(η⁶-C₆Me₆)Ru(μ-Cl)Cl]₂, respectively. The X-ray crystal structure analyses of [<b>1</b>][PF₆], [<b>3</b>][PF₆] and [<b>6</b>][PF₆]2 reveal a typical piano-stool geometry around the metal centre; in the dinuclear complexes the two chloro ligands, with respect to each other, are found to be trans oriented.