Mohammed Yusuff, K K; Arun, Vasudevan; Sreedevi, N; Robinson, P P; Manju, Sebastian(Elsevier,Journal of Molecular Catalysis A: Chemical 304 (2009) 191–198, February 7, 2009)
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Abstract:
Two new complexes, [MII(L)(Cl)(H2O)2]·H2O (where M=Ni or Ru and L = heterocyclic Schiff base, 3-
hydroxyquinoxaline-2-carboxalidene-4-aminoantipyrine), have been synthesized and characterized by
elemental analysis, FT-IR, UV–vis diffuse reflectance spectroscopy, FAB-MASS, TG–DTA, AAS, cyclic
voltammetry, conductance and magnetic susceptibility measurements. The complexes have a distorted
octahedral structure andwere found to be effective catalysts for the hydrogenation of benzene. The influence
of several reaction parameters such as reaction time, temperature, hydrogen pressure, concentration
of the catalyst and concentration of benzenewas tested. A turnover frequency of 5372 h−1 has been found
in the case of ruthenium complex for the reduction of benzene at 80 ◦C with 3.64×10−6 mol catalyst,
0.34 mol benzene and at a hydrogen pressure of 50 bar. In the case of the nickel complex, a turnover
frequency of 1718 h−1 has been found for the same reaction with 3.95×10−6 mol catalyst under similar
experimental conditions. The nickel complex shows more selectivity for the formation of cyclohexene
while the ruthenium complex is more selective for the formation of cyclohexane
Mohammed Yusuff, K K; Mayadevi, S; Preetha, G Prasad(Taylor & Francis, May 5, 2003)
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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.