Syntheses, structures and photocatalytic properties of ruthenium(II) complexes supported by a tetradentate cyclen ligand (cyclen = 1,4,7,10-tetraazacyclododecane)

Abstract

Treatment of [(cyclen)RuCl(dmso)]Cl (cyclen = 1,4,7,10-tetraazacyclododecane, dmso = dimethylsulfoxide, 1) with zinc powder in the presence of potassium hexafluorophosphate or sodium perchlorate in acetonitrile afforded the cationic complexes [(cyclen)Ru(dmso)(MeCN)]Q2 (Q = PF6 (2), ClO4 (3)). Interaction of 1, zinc powder and 4-tert-butylpyridine or pyridine in the presence of triethylamine and sodium perchlorate gave pyridine-ruthenium(II) complexes Na[(cyclen)Ru(dmso)(4-tBupy)](ClO4)3 (4) and [(cyclen)Ru(py)2](ClO4)2 (5), respectively. While reactions of 1, zinc powder and 1,10-phenanthroline (phen) or 5,5′-dimethyl-2,2′-bipyridine (5,5′-Me2bpy) in the presence of triethylamine and potassium hexafluorophosphate gave bipyridine-ruthenium(II) complexes [(cyclen)Ru(phen)](PF6)2 (6) and [(cyclen)Ru(5,5′-Me2bpy)](PF6)2 (7), respectively. Complexes 1–7 are characterized by infrared, UV/Vis, NMR spectroscopies along with their electrochemistry properties. The molecular structures of complexes 1–7 have been established by single-crystal X-ray diffraction. The photocatalytic properties of complexes 6 and 7 with a large π-electron delocalized system for the H2 evolution by water reduction were also investigated in the paper.