ELECTRON BEHAVIOR AND STRUCTURAL CHARACTERIZATION OF NITROSYL PINCER-TYPE PNP RHODIUM COMPLEXES

CARINA GAVIGLIO; FABIO DOCTOROVICH; JUAN PELLEGRINO

Bariloche

Congreso; XV Reunión de la Asociación Argentina de Cristalografía; 2019

A topic of interest consists on exploring the combination of robust bulky pincer ligands that present high stability and steric protection with redox active ligands as NO in the reactivity of {RhNO}n complexes. Nitrosyl complexes are described as {MNO}n where n stands for the number of electrons in the metal d and π* NO orbitals. In a previous work the activation of carbon-halogen bonds by a paramagnetic complex {RhNO}9 with a PCP pincer type ligand was reported [1]. Herein the synthesis and characterization of a new paramagnetic complex {RhNO}9 1+. with a PNP pincer type ligand is presented.Reaction of {RhNO}8 12+ with 1 equivalent of Co(Cp)2 in trifluorotoluene resulted in quantitative formation of 1+. and [Co(Cp)2][BF4]. The paramagnetic nature of the one-electron reduced {RhNO}9 species 1+. was confirmed by EPR and by the broad resonances occurring in 1H NMR. Also by FTIR the expected change was observed in the NO upon the {RhNO}89 conversion from 12+ to 1+. (1911 to 1650 cm-1). Figure 1: ORTEP plot of complexes 12+ and 1+. at the 50% probability level. Hydrogen atoms and triflate counterions (CF3SO3-) are omitted for clarity.The molecular structure of both compounds 12+ and 1+. was confirmed by X-ray diffraction (Figure 1). In both structures the rhodium atom is located in the center of a square-planar geometry with the nitrosyl group occupying the position trans to the ipso carbon. In 12+ the Rh-N-O angle is 176.1(3)º while in 1+. is 145.5(2)º due to the more electron density on the NO ligand.Palabras clave: nitrosyl complexes; DRX; redox behavior.[1] J. Pellegrino, C. Gaviglio, D. Milstein, F. Doctorovich, Organometallics, 32 (2013) 6555-6564.