Research projects at Lisbon
Organometallic and Coordination Chemistry at Metal Centres with Biological Significance
Positions for ESR grants are immediately available for 6 – 12 months, subject to renewal, and are expected to allow the candidate to continue for D.Phil. studies under a subsequent national fellowship.
The mode of action of nitrogenases, the nitrogen fixation enzymes, towards the activation of their substrates still constitutes an intriguing matter, in spite of some noteworthy achievements like the establishment of the molecular structure of the cofactor and the stepwise protic reduction of N2 to ammonia at a suitable transition metal centre in non-aqueous medium.
Our Group has been engaged on the activation, by coordination to dinitrogen-binding metal centres, of a variety of small molecules of biological significance, including alternative nitrogenase substrates like isocyanides, nitriles, cyanide, cyanamide, alkynes and azide. In particular by ligating an electron-rich metal centre, with a high pi-electron-releasing ability, those substrates undergo ready protonation to afford multiple metal-carbon and metal-nitrogen bonded products which can be postulated as intermediates in the enzymatic reductions.
In the current project we plan to extend some of that chemistry, aiming to mimic the biological function of nitrogenase and other enzymes like nitrile hydratase (hydrolysis of nitriles to carboxamides and other products) and methane monoxygenases (partial oxidation of alkanes, including methane, to products with commercial added value).
The project entails a preparative stage, with the synthesis of appropriate complexes, namely with some of those substrates or appropriate reagents, followed by the investigation of their reactivity towards conversion into the enzymatic products.
Electrochemical methods will also be applied to study the electronic properties of the metal centres and ligands and to activate them by electron-transfer towards further chemical reactions.
Requirements: Highly motivated candidate for D. Phil. degree with a good mark in the licentiate or M.Sc. course (application to a D. Phil. fellowship, under a national programme, to further the Network position, is expected after the researcher gets the required experience); basic knowledge in coordination and organometallic chemistry; basic experience on the synthesis and handling of air-sensitive compounds is advisable.
1- V. Yu. Kukushkin and A.J.L.Pombeiro, “Additions to Metal-Activated Organonitriles”, Chem. Rev., 2002, 102, 1771-1802.
2- S.M.P.R. Cunha, M.F.C. Guedes da Silva and A.J.L. Pombeiro, “Mixed Dinitrogen- Organocyanamide Complexes of Molybdenum(0) and Their Protic Conversion into Hydrazine and Amidoazavinylidene Derivatives”, Inorg. Chem., 2003, 42, 2157-2164.
4- P.M. Reis, J.A.L. Silva, A.F. Palavra, J.J.R. Fraústo da Silva, T. Kitamura, Y. Fujiwara and A.J.L. Pombeiro, “Single-pot Conversion of Methane into Acetic Acid, in the Absence of CO and with Vanadium Catalysts Such as Amavadine”, Angew. Chem., Intern. Ed.: 2003, 42, 821-823.
5- P.M. Reis, J.A.L. Silva, A.F. Palavra, J.J.R. Fraústo da Silva and A.J.L. Pombeiro, “Vanadium-Catalyzed Carboxylation of Linear and Cyclic C5 and C6 Alkanes”, J. Catal., 2005, 235, 333-340.
6- Q. Li, M.F.C. Guedes da Silva and A.J.L. Pombeiro, “Diorganotin(IV) Derivatives of Substituted Benzohydroxamic Acids with High Antitumor Acticvity”, Chem. Eur. J., 2004, 10, 1456-1462.
7- A.J.L. Pombeiro, “Comparative Behaviours of Phospha-alkynes and Alkynes at Electron- rich Phosphinic Metal Centres”, J. Organometal. Chem., 2001, 632, 215-226.
8- A.J.L. Pombeiro, M.F.C. Guedes da Silva and R.A. Michelin, “Aminocarbyne Complexes Derived from Isocyanides Activated Toward Electrophilic Addition”, Coord. Chem. Rev., 2001, 218, 43-74.
Cost of living in Lisbon: Accommodation: from ca. 220 euros/month (single room in a shared flat or family); other living expenses: ca. 300 euros/month.
Centro de Química Estrutural
Complexo I, Instituto Superior Técnico
Av. Rovisco Pais, 1049-001 Lisboa, Portugal