ELECTRONIC EFFECTS ON SINGLE SITE IRON CATALYST WATER OXIDATION

Zoel Codolà Irene Prat Isaac Garcia-Bosch Miquel Costas Julio Lloret Fillol
Departament de Química, Universitat de Girona, Girona


The substitution of earth-scarce transition metals for a most available redox core is a fundamental step for a sustainable oxygen production,1-4 the bottle-neck of the water splitting process. A family of iron-based complexes with neutral tetradentate organic ligands5 was able to perform the water oxidation using CAN and NaIO4 as a sacrificial oxidizing reagents, becoming a real alternative and non-expensive water oxidation catalysts (WOCs). We showed a new well-defined iron based catalysts with readily available and straightforward to modify tetradentate nitrogen ligands.5 In this communication, we will focus on the study of the electronic influence imposed by the ligand by introducing different groups at the para- position of the pyridine [Fe(OTf)2(4-EPytacn)] (E = H, Cl, CO2Et, NO2). Remarkably, in all new complexes higher efficiencies were obtained, allowing us to increase more than 2 folds in oxygen evolution respect to complex 1; previously reported as one of the best iron WOC so far. A deep kinetic study aided us to understand the first steps of the mechanism and to postulate that FeV is the key reactive specie.5

 

Schematic representation of the catalysts used in this work

1. Brimblecombe, R., Swiegers, G. F., Dismukes, G. C. & Spiccia, L.Angew. Chem. Int. Ed., 2008, 47, 7335.

2. Ellis,WC., McDaniel, ND., Bernhard,S., Collins, T.J., J. Am. Chem. Soc., 2010, 132, 10990.
3. Kanan, M. W. & Nocera, D. G, Science,,2008, 321, 1072.
4. Qiushi Yin, J. M. T., Claire Besson, Yurii V. Geletii, Djamaladdin G. Musaev, Aleksey E. Kuznetsov, Zhen Luo, Ken I. Hardcastle, Craig L. Hill Science, 2010, 328, 34.
5. Lloret Fillol, J., Codolà, Z., Garcia-Bosch, I., Gómez, L., Pla, J.J., Costas, M. Nat.Chem, 2011, 3, 807.








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