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Abstract:
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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. |