Rip It off: Nitro to Nitroso Reduction by Iron Half-Sandwich Complexes

Marcus Korb (1) , Seyed Mohammad Bagher Hosseini Ghazvini (1) , Stephen A Moggach (1) , Jean-François Meunier (2) , Azzedine Bousseksou (2) , Paul Low (1)

1 UWA - The University of Western Australia
2 LCC - Laboratoire de chimie de coordination

Activation of [FeCl(dppe)Cp] (1) by chloride abstraction with Na[BArX4] (X = F, [B(3,5-(CF3)2-C6H3)4]; X = Cl, [B(3,5-Cl2-C6H3)4]) permits reactions with a range of nitro aromatics, RC6H4NO2 (R = halogen, Me, OMe, NO2 or NMe2), to give the cationic iron nitroso complexes [Fe{N(O)-C6H4R}(dppe)Cp][BArX4]) ([3][BArX4]). Similar reactions of 1 and Na[BArX4] with [Fe(NCC6H4NO2)(dppe)Cp][BArX4] gave bimetallic [{Fe(dppe)Cp}2{μ-N≡CC6H4N(O)}][BArF4]2. However, reactions of 1 and Na[BArX4] with 4-nitrophenol gave the first example of the bench-stable iron half-sandwich phenolate complex [Fe(OC6H4NO2)(dppe)Cp]+ rather than NO2 activation. The formation of complexes [3]+ likely proceeds via the unusual blue bimetallic species [{Fe(dppe)Cp}2{μ,κ2O,O′-O2NAr}]2+. This compound undergoes N–O bond cleavage, resulting in [3]+ and a FeIV═O species, which reacts via an internal C–H activation of the dppe ligand to give [FeIII(κ3O,P,P′-P(2-O-C6H4)(Ph)-C2H4-PPh2)Cp]+. Complexes [3]+ are stable under ambient conditions, are readily purified by column chromatography and can be isolated in up to 50% yield, considering that 0.5 equiv of 1 is required as the oxygen acceptor.

Mots clés: Substituents; Oxygen; Iron; Metals; Ligands

Domaines: Chimie de coordination; Catalyse; Chimie organique

Marcus Korb, Seyed Mohammad Bagher Hosseini Ghazvini, Stephen A Moggach, Jean-François Meunier, Azzedine Bousseksou, et al.. Rip It off: Nitro to Nitroso Reduction by Iron Half-Sandwich Complexes. Inorganic Chemistry, 2021, 60 (7), pp.4986-4995. ⟨10.1021/acs.inorgchem.1c00042⟩. ⟨hal-03225433⟩