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 (N-2)(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 degrees C under argon have EPR spectra containing a doublet at g(iso) = 1.976 with a 110 G hyperfine coupling constant. The solutions react with N-2 to generate (N-2)(2-) and (N-2)(3-) complexes {[(Me3Si)(2)N](2)(THF)Y}(2)(mu-eta(2):eta(2)-N-2) (1) and {[(Me3Si)(2)N](2)(THF)Y}(2)(mu-eta(2):eta(2)-N-2)[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 (N-2)(3-) radical with proton sources was probed for the first time for comparison with the (N-2)(2-) and (N-2)(4-) chemistry. Complex 2 reacts with [Et3NH] [BPh4] to form {[(Me3Si)(2)N](2)(THF)Y}(2)(mu-N2H2), the first lanthanide (N2H2)(2-) complex derived from dinitrogen, as well as 1 as a byproduct, consistent with radical disproportionation reactivity.