Synthesis of the (N2)3− Radical from Y2+ and Its Protonolysis Reactivity To Form (N2H2)2− via the Y[N(SiMe3)2]3/KC8 Reduction System

Examination of the Y[N(SiMe3)2]3/KC8 reduction system that allowed isolation of the (N2)3− radical has led to the first evidence of Y2+ in solution. The deep-blue solutions obtained from Y[N(SiMe3)2]3 and KC8 in THF at −35 °C under argon have EPR spectra containing a doublet at giso = 1.976 with a 110 G hyperfine coupling constant. The solutions react with N2 to generate (N2)2− and (N2)3− complexes {[(Me3Si)2N]2(THF)Y}2(μ-η2:η2-N2) (1) and {[(Me3Si)2N]2(THF)Y}2(μ-η2:η2-N2)[K(THF)6] (2), respectively, and demonstrate that the Y[N(SiMe3)2]3/KC8 reaction can proceed through an Y2+ intermediate. The reactivity of (N2)3− radical with proton sources was probed for the first time for comparison with the (N2)2− and (N2)4− chemistry. Complex 2 reacts with [Et3NH][BPh4] to form {[(Me3Si)2N]2(THF)Y}2(μ-N2H2), the first lanthanide (N2H2)2− complex derived from dinitrogen, as well as 1 as a byproduct, consistent with radical disproportionation reactivity.