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

MARÍA SOL SANTALLA; CARINA GAVIGLIO; JUAN PELLEGRINO

Otro; LatinXChem 2020; 2020

The study of nitrosyl compounds is interesting because theNO ligand has three redox states: NO+, NO- and NO?, so using that ligand as anactive redox ligand, it is possible to increase the oxidation state changes ina complex. The use of redox ?noninnocent? ligands as reservoirs of electrons isan interesting approach for bond-making and bond breaking reactions atcoordinatively unsaturated metals. In addition, paramagnetic nitrosyl complexeshave 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 toobtain the {MNO}9 forms through their respective reductions.On one hand, thecomplex [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 whichit was concluded that the reduction is irreversible.When performing thereduction with cobaltocene, the mixture of three diamagnetic complexes wasobtained, 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 analternative 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 wasstudied by cyclic voltammetry, from which it was concluded that the reductionis irreversible. Its reduction was accomplished with Co(Cp*)2, which is astronger reductant than cobaltocene and the product was characterized by31P-NMR, 1H-NMR and FTIR. The information acquired would indicate that perhapsa paramagnetic complex {RuNO}9 was not obtained, however, studies are stillbeing 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 Metalesde Transición con el Ligando Rédox Activo NO: estructura electrónica,interconversión y reactividad". Tesis doctoral, Universidad de BuenosAires, 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.