Coupling of Nitric Oxide and Release of Nitrous Oxide from Rare-Earth-Dinitrosyliron Complexes

Addition of Lewis acidic [Cp*₂M]⁺ (M = Y, Gd) to the dinitrosyliron complexes (DNICs) [(NacNac^Ar)­Fe­(NO)₂]⁻ (Ar = mesityl, 2,6-diisopropylphenyl) results in formation of the isonitrosyl-bridged DNICs [(Cp*)₂M­(μ-ON)₂­Fe­(NacNac^Ar)]. When Ar = 2,6-diisopropylphenyl, coupling of the NO ligands and release of N₂O occur. Two factors contribute to this previously unobserved DNIC reactivity mode. First, the oxophilic rare-earth elements drive the formation of isonitrosyl bonds, forcing the DNIC nitrogen atoms into proximity. Second, the bulky substituents further squeeze the DNIC, which ultimately overcomes the barrier to NO coupling, demonstrating that N₂O elimination can occur from a single iron center.