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

More documents

Recommendations

Info

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
XII Iberian Meeting of Electrochemistry & XVI Meeting of the Portuguese Electrochemical Society PE 06 Electrochemical behaviour of C-functionalized or substitutedpyrazolyl scorpionate cobalt complexes Telma F.S. Silva, 1 Luísa M.D.R.S. Martins, 1,2 Armando J.L. Pombeiro 1 1 Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Av. Rovisco Pais, 1049- 001 Lisboa, Portugal. 2 Área Departamental de Engenharia Química, ISEL, R. Conselheiro Emídio Navarro, 1959-007 Lisboa, Portugal. tsilva@dem.isel.ipl.pt Scorpionates have become well-established as ligands in coordination and organometallic chemistry, and their complexes have made important contributions in numerous different areas, such as modeling of metallo-enzymes and catalysis. 1 In pursuit of our interest on the coordination chemistry of C-scorpionates towards several transition metals, 2 we now report the electrochemical study of our recently obtained half- or full-sandwich cobalt complexes 1-4 prepared by reaction of cobalt(II) chloride with LiSO 3 C(pz) 3 , HC(pz Ph ) 3 or OHCH 2 C(pz) 3 (pz = pyrazolyl): [Co{HC(pz) 3 }(OSO 2 OH)(OCH 3 ) 2 ] 1, [CoCl 2 {3Ph-pzH} 3 ] 2 2, [Co{3Ph-pzH} 4 ]Cl 2 3 or [Co{OHCH 2 C(pz) 3 } 2 ].[Co{OHCH 2 C(pz) 3 }(H 2 O) 3 ](Cl) 2 .2H 2 O 4. All the studies have been carried out by cyclic voltammetry (CV) at a Pt-disc electrode or controlled potential electrolysis (CPE) at a Pt-gauze electrode, in a 0.2 M Bu 4 NBF 4 /NCMe or DMSO solution. The electrochemical behaviours are discussed in terms of electron richness of the Co centres and the electronic properties of the ligands. Fig.1 - Cyclic voltammograms of 4, initiated by the anodic sweep, at a Pt disc electrode, in a 0.20 M n Bu 4 N[BF 4 /NCMe solution, in the scan rate range 50 - 400 Vms -1 . Acknowledgments: This work has been partially supported by the Fundação para a Ciência e a Tecnologia (F CT), Portugal, and its PCDT (F EDER funded) programme. TFSS is grateful to F CT for a PhD grant (no. SFRH/BD/48087/2008). References [1] C. Pettinari, Scorpionates II: Chelating Borate Ligands - Dedicated to Swiatoslaw Trofimenko, Imperial College Press, World Scientific Pub., 2008. [2] a) T.F.S. Silva, K.V. Luzyanin, M.V. Kirillova, M.F. Guedes da Silva, L.M.D.R.S. Martins, A.J.L. Pombeiro, Adv. Synth. Catal., 2010, 352, 171. b) T.F.S. Silva, E.C.B.A. Alegria, L.M.D.R.S. Martins, A.J.L. Pombeiro, Adv., Synth. Cat., 2008, 350, 706. c) R. Wanke, P. Smolenski, M.F.C. Guedes da Silva, L.M.D.R.S. Martins, A.J.L. Pombeiro, Inorg. Chem., 2008, 47, 10158. September, 811, 2010. ISEL - Lisbon 97
Page 1 and 2:
SPECIAL ISSUE 2010 ABSTRACTS BOOK X
Page 3 and 4:
XII Iberian Meeting of Electrochemi
Page 5 and 6:
Page 7 and 8:
Page 9 and 10:
Page 11 and 12:
Page 13 and 14:
Page 15 and 16:
Page 17 and 18:
Page 19 and 20:
Page 21 and 22:
Page 23 and 24:
Page 25 and 26:
Page 27:
Page 30 and 31:
Page 32 and 33:
Page 34 and 35:
Page 36 and 37:
Page 38 and 39:
Page 40 and 41:
Page 42 and 43:
Page 44 and 45:
Page 46 and 47:
Page 48 and 49:
Page 50 and 51: XII Iberian Meeting of Electrochemi
Page 99: XII Iberian Meeting of Electrochemi
show all

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

Create successful ePaper yourself

Delete template?

Save as template?