Dinitrogen Functionalization Affording Chromium Diazenido and Side-on η²-Hydrazido Complexes

Zhu-Bao Yin, Botao Wu, Gao-Xiang Wang, Junnian Wei^*, Zhenfeng Xi^*

J. Am. Chem. Soc., 2023. DOI: 10.1021/jacs.3c00266.

  Isolation of key intermediate complexes in dinitrogen functionalization is crucial for elucidating the mechanistic details and further investigation. Herein, the synthesis and characterization of (μ-η¹:η¹-N₂)(η¹-N₂)-Cr(I) 3 and (η¹-N₂)₂-Cr(0) complexes 4 supported by Cp* (Cp* = C₅Me₅) and NHC ligands were reported. Further functionalization of Cr(0)-N₂ complex 4 with silyl halides delivered the key intermediates in the alternating pathway, the chromium diazenido complex 5 and the chromium side-on η²-hydrazido complex 6. Protonation of 6 led to the quantitative formation of N₂H₄. Moreover, the [η²-Me₃SiNNSiMe₃]^2– unit in 6 enabled N–C bond formation reactions with CO₂ and ^tBuNCO, giving the corresponding N,O-chelating hydrazidochromium complexes 7 and 8, respectively.