Synthesis, structure and reactivity of NO + , NO˙ and NO − pincer PCN-Rh complexes

GALLEGO, CECILIA MARIEL; GAVIGLIO, CARINA; BEN-DAVID, YEHOSHOA; MILSTEIN, DAVID; DOCTOROVICH, FABIO; PELLEGRINO, JUAN

DALTON TRANSACTIONS

ROYAL SOC CHEMISTRY

Año: 2020 vol. 49 p. 7093 - 7108

1477-9226

Synthesis of a pincer-type linear nitrosyl complex [Rh(PtBu2CNEt2)(NO)]+ (3+) is described. The product and all intermediates involved were fully characterized by FTIR, NMR, cyclic voltammetry and X-ray crystallography. Attempts at obtaining (3+) from its chlorinated precursor Rh(PCN)(NO)Cl (2) revealed that a relative stabilization of this complex ion is introduced by the BArF− counteranion, as other counteranions ? PF6−, BF4− and triflate- proved to coordinate to the metal center. Redox reactivity both of (3+) and of that of its five-coordinate derivatives (2) and [Rh(PCN)(NO)(CH3CN)]+ (4+) was found to distinguish itself from analogous PCP complexes due to a relative stabilization of higher oxidation states. Oxidation of these three complexes was studied by FTIR spectroelectrochemistry. Reduction of complex (3+) to yield a short-lived {RhNO}9 species [Rh(PCN)(NO)]? (3?) was also carried out. Complex (3?) was proved able to activate carbon-halogen bonds in aryl halides, in much a similar way as that of its PCP analogue. Complex (3+) was also seen to establish a linear↔bent nitrosyl equilibrium upon addition of CO which could not be fully displaced with excess CO.