XII Iberian Meeting of Electrochemistry XVI Meeting of the ...

XII Iberian Meeting of Electrochemistry & XVI Meeting of the Portuguese Electrochemical Society PE 05
Electrochemical studies of Cu I -scorpionate complexes
Riccardo Wanke, 2 Luísa M.D.R.S. Martins, 1,2 Armando J.L. Pombeiro 2
1 Área Departamental de Engenharia Química, ISEL, R. Conselheiro Emídio Navarro, 1959-007
Lisboa, Portugal. 2 Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Av.
Rovisco Pais, 1049-001 Lisboa, Portugal
lmartins@deq.isel.ipl.pt
Metal complexes of scorpionate ligands, in particular of tris(pyrazolyl)borates (Tp),
constitute one of the most extensively studied classes in inorganic, organometallic and
bioinorganic chemistries.
The study we now report aimed at the synthesis and investigation of the coordination
ability of a new C-scorpionate that could combine flexibility and water solubility with
the sterically demanding features of the 3-substituted tris(pyrazolyl) ligands. For these
purposes, we designed the new sterically hindered tris(1-pyrazolyl)methane sulfonate
[SO 3 C(pz Ph ) 3 ] - , (Tpms Ph ) - derivative, bearing a phenyl group at the 3-position of the
pyrazolyl rings (Fig. 1). When ligating a metal centre, such a bulky species would be
tion position(s) of the
complex.
A series of copper(I) complexes bearing
(Tpms Ph ) - has been prepared 1 and the
electrochemical behaviour has been studied
by cyclic voltammetry and controlled
potential electrolysis at Pt electrodes,
namely for complexes such as
[Cu(Tpms Ph )(MeCN)] (1) and
[Cu(Tpms Ph )(PTA)] (2) (PTA = 1,3,5-
triaza-7-phosphaadamantane).
Complexes 1 and 2 display an irreversible
process ascribed to the Cu(I) to Cu(II)
Fig.1
oxidation.
The electrochemical behaviour of the above complexes has been interpreted in terms of
the electronic properties of the ligands and confirms the observed 1 solution 1 H-NMR
and solid state X-ray diffraction data. For instance, for 2 the higher electron withdrawing
effect of the ligated phosphine (i.e. PTA) hampers the oxidation of metal center and
favours the N,N,N-coordination mode of the scorpionate ligand, whereas at 1, Tpms Ph
adopts the less electron releasing N,N,O-mode.
Acknowledgements: This work has been partially supported by the Foundation for Science and
Technology (F CT), Portugal, and its PPCDT
References
[1] Wanke, R.; Smolénski, P.; Guedes da Silva, M. F. C.; Martins, L. M. D. R. S., Pombeiro, A. J.
L., Inorg. Chem., 2008, 47, 10158.
September, 811, 2010. ISEL - Lisbon 96