Redox Behaviour of {MNO}8 Complexes of Iron and Ruthenium

MARÍA SOL SANTALLA; CARINA GAVIGLIO; JUAN PELLEGRINO

(Virtual)

Congreso; LatinXChem 2020; 2020

The study of nitrosyl compounds is interesting because the NO ligand has three redox states: NO+, NO- and NO, so using that ligand as an active redox ligand, it is possible to increase the oxidation state changes in a complex. The use of redox noninnocent ligands as reservoirs of electrons is an interesting approach for bond-making and bond breaking reactions at coordinatively unsaturated metals. In addition, paramagnetic nitrosyl complexes have been shown to be efficient for the activation of C-X bonds [1],[2]. Nitrosyl complexes are described by the Enemark-Feltham notation as {MNO}n [3].In this work, complexes {FeNO}8 and {RuNO}8 were prepared, in order to obtain the {MNO}9 forms through their respective reductions.On one hand, the complex [Fe(CO)2NO(PPh3)2]+ was prepared. [4][Fe(CO)3(PPh3)2]+NOBF4 --->[Fe(CO)2(NO)(PPh3)2][BF4] (1)+COComplex 1 was characterized by 31P-NMR, 1H-NMR, FTIR and X-ray diffraction, obtaining a structure that is not reported. In addition, its redox behavior was studied by cyclic voltammetry, from which it was concluded that the reduction is irreversible.When performing the reduction with cobaltocene, the mixture of three diamagnetic complexes was obtained, and not the desired paramagnetic complex {FeNO}9 .On the other hand, the synthesis of the complex [Ru(NO) (PPh3)2Cl] was carried out by an alternative route to that reported [5].[Ru(NO)Cl3(PPh3)2]+2Co(Cp)2--->[Ru(NO)(PPh3)2Cl] (2)Complex 2 was characterized by 31P-NMR, FTIR and X-ray diffraction, obtaining a structure that is not reported. In turn, its redox behavior was studied by cyclic voltammetry, from which it was concluded that the reduction is irreversible. Its reduction was accomplished with Co(Cp*)2, which is a stronger reductant than cobaltocene and the product was characterized by 31P-NMR, 1H-NMR and FTIR. The information acquired would indicate that perhaps a paramagnetic complex {RuNO}9 was not obtained, however, studies are still being carried out to establish the identity of the products of the reaction of (2) and Co (Cp*)2.[1] J. Pellegrino, C.Gaviglio, D. Milstein, F. Doctorovich. Organometallics, 2013, 32, 6555.[2] Pellegrino, J. "Complejos de Metales de Transición con el Ligando Rédox Activo NO: estructura electrónica, interconversión y reactividad". Tesis doctoral, Universidad de Buenos Aires, 2013.[3] Enemark, J. H.; Feltham, R. D. Coord. Chem. Rev. 1974, 13, 339.[4] B. F. G. Johnson, J. A. Segal, J. Chem. Soc. Dalton Trans., 12 (1972) 1268.[5] J. Reed, CG . Pierpont and R. Eisenberg, Inorg. Synth., 16 (1976) 21.