Structural, Magnetic, Thermal, Electrochemical and Chemical
Properties of Binuclear Complexe of Copper(II) Benzoate
Mohamadin1, M.I. and Abdullah1, N.
1
Chemistry Department, Faculty of Science, University of Malaya, 50603 Kuala Lumpur,
Malaysia
misa@sarawak.uitm.edu.my
Copper(II) benzoate has been synthesized and characterized by analytical, spectral,
magnetic, thermal and electrochemical methods. The X-Ray crystal structure show that the
compound has a binuclear paddle-wheel structure similar to copper(II) acetate
monohydrate. The IR absorption bands for the carboxylate group are within the ranges:
 as = 1562 cm-1,  s = 1408 cm-1 and  = 154 cm-1 which agrees with the dimeric
structure of copper(II) benzoate with tetracarboxylate bridges. The presence of Band II ( ~
380 nm) in electronic spectrum for copper(II) benzoate further supports the dimeric and
bridging structure of the complex. The thermal stability of the complexe was studied by
thermogravimetry. This complexe starts to decompose well above 150 oC, and generally
follow a one- to two-step decomposition process. The magnetic moments over room
temperature was also investigated for all compounds. The compound show moments
considerably smaller than the spin moment for one unpaired electron indicating a strong
spin interaction in the compound. The voltammetric behaviour of the compound was also
investigated in acetic acid-methanol mixture as solvent by cyclic voltammetry using
TBATFB (tetrabutylammonium tetrafluoroboric) supporting electrolyte. The cyclic
voltammograms showed three reduction waves attributed to the formation of Cu(I) ion in
the solution as well as the plating of the electrodes. The presence of one big oxidation wave
might indicate that the disproportionation procees has taken place. Copper(II) benzoate also
has property to mediate the C-C bond formation in carbonyls. The presence of copper(II)
benzoate in the reaction has been found to assist the C-C bond-forming reaction of aliphatic
ketones, aromatic ketones, two different ketones and a ketone and aldehyde. The reaction
mechanism is believed to involve the reduction of copper(II) to copper(I) followed by the
formation of an enone and finally formation of a stable Cu(I) complex.