Synthesis, spectroscopic characterization and catalytic oxidation properties of ONO/ONS donor Schiff base ruthenium(III) complexes containing PPh₃/AsPh₃

S PRIYAREGA^a, M MUTHU TAMIZH^b, R KARVEMBU^b, R PRABHAKARAN^a and K NATARAJAN^a,*

^aSchool of Chemistry, Bharathiar University, Coimbatore 641 046, India

^bDepartment of Chemistry, National Institute of Technology, Tiruchirappalli 620 015, India

*Corresponding author. E-mail: k_natraj6@yahoo.com

MS received 6 July 2010; revised 3 January 2011; accepted 4 March 2011

Abstract. Six different ruthenium(III) complexes of Schiff bases derived from 2-hydroxy-1-naphthaldehyde and o-aminophenol/o-aminothiophenol have been synthesized. The compounds with the general formula [RuX(EPh₃)₂(L)] (X = Cl or Br; E = P or As; L = bifunctional tridentate ONO/ONS donor Schiff base ligand) were characterized by infrared, electronic, electron paramagnetic resonance spectroscopy and elemental analyses. Spectroscopic investigation reveals coordination of Schiff base ligand through ONO/ONS donor atoms and octahedral geometry around ruthenium metal. Redox property of complexes has been examined by using cyclic voltammetry. The catalytic oxidation property of ruthenium(III) complexes were also investigated.

Graphical Abstract. Mononuclear Ru(III) complexes of the type [RuX(EPh₃)₂(L)] (X = Cl or Br; E = P or As; L = bifunctional tridentate Schiff base ligand) were prepared and characterized by UV-Vis, IR and EPR spectroscopy. Electrochemical behaviour of the complexes has been examined. The complexes act as catalysts for the oxidation of alcohols to carbonyl compounds in the presence of N-methylmorpholine-N-oxide.

Keywords. Ruthenium(III); Schiff base ligand; triphenylphosphine; triphenylarsine; catalytic oxidation.