Stable mononuclear and binuclear ruthenium(II) arene complexes with multiple N-donor poly-pyridyl ligands: synthesis, spectroscopic and structural characterization. Single crystal X-ray structure of [(η6-C10H14)RuCl(bppz)]BF4

The reaction of 2,3-bis(2-pyridyl)-pyrazine (bppz) with dimeric chloro-bridged arene ruthenium complexes [{(η6-arene)RuCl2}2] (arene=p-cymene or hexamethyl benzene) gives highly stable cationic mono and binuclear complexes with the formulation [(η6-C10H14)RuCl(bppz)]+ and [{(η6-C10H14)RuCl}2(μ-bppz)]2+. On the contrary, reactions of the potential bridging ligand 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) or 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz) with the chloro-bridged dimeric arene ruthenium complexes [{(η6-arene)RuCl2}2] under similar reaction conditions led to the formation of binuclear complexes with the formulation [{(η6-arene)RuCl}2(μ-L)]2+ (where η6-arene=p-cymene or hexamethyl benzene and L=tptz or bptz). The reaction products were characterized by various physico-chemical techniques, viz. elemental analyses, IR, 1H–1H COSY, 1H-, 13C-NMR, FAB mass spectroscopy and electronic spectral studies. Molecular structure of the representative mononuclear complex [(η6-C10H14)RuCl(bppz)]BF4 was determined by single crystal X-ray diffraction analysis. Crystal data: monoclinic, C2/c, a=16.103(5) Å, b=16.207(2) Å, c=19.124(2) Å, β=91.61(2)°, Z=8, R=0.0714.