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

Abstract

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.