Studies on Some Transition Metal Complexes of Schiff Bases Derived from Quinoxaline‐2‐carboxaldehyde

Abstract

Two series of transition metal complexes of Schiff bases derived from quinoxaline‐2‐carboxaldehyde with semicarbazide (QSC) and furfurylamine (QFA) were synthesised and characterised by elemental analyses, molar conductance and magnetic susceptibility measurements, IR, electronic and EPR spectral studies. The QSC complexes have the general formula [M(QSC)Cl₂]. A tetrahedral structure has been assigned for the Mn(II), Co(II) and Ni(II) complexes and a square‐planar structure for the Cu(II) complex. The QFA complexes have the formula [M(QFA)₂Cl₂]. An octahedral structure has been assigned for these complexes. All of the complexes exhibit catalytic activity towards the oxidation of 3,5‐di‐tert‐butylcatechol (DTBC) to 3,5‐di‐tert‐butylquinone (DTBQ) using atmospheric oxygen. The cobalt(II) complex of the ligand QFA was found to be the most active catalyst.

Keywords:

• Quinoxaline‐2‐carboxaldehyde
• Semicarbazide
• Furfurylamine
• Schiff base
• Manganese(II)
• Cobalt(II)
• Nickel(II)
• Copper(II)
• Transition metal complexes
• 3,5‐Di‐tert‐butylcatechol
• Catalytic oxidation

Acknowledgments

Two of us, S.M. and P.G.P. are grateful to the Council of Scientific and Industrial Research, New Delhi, for the award of Research Associateship and Junior Research Fellowship, respectively.