Redox behavior of {MNO}8 of iron and ruthenium

MARÍA SOL SANTALLA; CARINA GAVIGLIO; JUAN PELLEGRINO

CABA

Simposio; Exploring the Frontiers of Chemistry: Challenges for the 21st Century; 2019

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 acomplex. The use of redox noninnocent ligands as reservoirs of electrons is an interesting approach forbond-making and bond breaking reactions at coordinatively unsaturated metals. In addition, paramagneticnitrosyl complexes have been shown to be efficient for the activation of C-X bonds [1],[2]. Nitrosyl complexesare 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 throughtheir 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 isnot 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 routeto that reported [5].[Ru(NO)Cl3(PPh3)2]+2Co(Cp)2--->[Ru(NO)(PPh3)2Cl] (2)Complex 2 was characterized by 31P-NMR and FTIR. Also, an attempt was made to characterize it by DRX,however, the structure [Ru(PPh3)2Cl2] was obtained, probably due to decomposition of 2 during thecrystallization process. In turn, its redox behavior was studied by cyclic voltammetry, from which it wasconcluded that the reduction is irreversible. Its reduction was accomplished with Co(Cp*)2, which is astronger reductant than cobaltocene and the product was characterized by 31P-NMR, 1H-NMR and FTIR.The information obtained would indicate that a paramagnetic complex {RuNO}9 was obtained, however,studies are still being carried out establish the identity of the product.[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: estructuraelectrónica, 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.