Synthesis and characterization of some new mononuclear ruthenium complexes containing 4-(un)substituted dipyridylpyrazole ligands

• Published in: Polyhedron 2008-03, Vol.27 (4), p.1168-1176
• Main Authors: Zhang, Wei, Liu, Jian-Hui, Pan, Jing-Xi, Li, Ping, Sun, Li-Cheng
• Format: Article
• Language: English
• Subjects: Dipyridylpyrazole derivatives; Ruthenium complex; X-ray diffraction
• ISSN: 0277-5387; 1873-3719
• DOI: 10.1016/j.poly.2007.12.023

A mononuclear Ru complex [Ru(bpy) 2(bpp)](PF 6) ( 1) and its halogenated and nitro derivatives [Ru(bpy) 2( Xbpp)](PF 6) (bpy = 2,2′-bipyridine; bpp = 3,5-bis(2-pyridyl) pyrazole; X = Cl, 2; X = Br, 3; X = I, 4; X = NO 2, 5) have been synthesized and characterized by 1H NMR, 13C NMR, HRMS and elemental analysis. Complexes 2– 5 have been further confirmed by X-ray diffraction. Their UV–Vis and emission spectroscopies, electrochemical measurements and acid–base properties are described. A mononuclear ruthenium complex [Ru(bpy) 2(bpp)](PF 6) ( 1) and its halogenated and nitro derivatives [Ru(bpy) 2( Xbpp)](PF 6) (bpy = 2,2′-bipyridine; bpp = 3,5-bis(2-pyridyl)pyrazole; X = Cl, 2; X = Br, 3; X = I, 4; X = NO 2, 5) have been synthesized and characterized by 1H NMR, 13C NMR, HRMS, elemental analysis. Complexes 2– 5 have been further confirmed by X-ray diffraction. Their UV–Vis and emission spectroscopies, electrochemical measurements and acid–base properties are described. The results presented here reveal that the introduction of Cl, Br, I and NO 2 groups to the coordinated bpp − ligand makes the absorption and emission maxima of the parent complex 1 blue-shifted, the oxidation potential of the Ru II/Ru III couple increased and the p K a value decreased obviously. In addition, significant quenching of the emission by these groups is also observed.