Synthesis, Characterization, and Interconversion of β-Diketiminato Nickel NxHy Complexes

The beta-diketiminato nickel(II) hydrazido(-1) complex [(LNi)-Ni-tBu(eta(2)-(NH3)-H-2)], (IV) was investigated with respect to its deprotonation/protonation behavior. Deprotonation with KOtBu led to [(LNi)-Ni-tBu(mu,eta(2):eta(2)-N2H2) K(solv)] (1), and this process was proven to be reversible. Spectroscopic and DFT studies revealed an electronic structure intermediate between nickel(II) hydrazido(-2) and nickel(0) diazene. On the other hand, protonation of IV with [LutH]OTf reversibly generated the hydrazine complex [(LNi)-Ni-tBu(eta(2)-N2H4)] OTf (2). Warming a solution of IV led to N-N bond cleavage yielding the nickel(I) ammine complex [(LNi)-Ni-tBu(NH3)], (3). Hence, LtBuNi moieties were shown to effectively activate NxHy species for diverse conversions.