Dinitrogen Reduction and Functionalization by a Siloxide Supported Thulium‐Potassium Complex for the Formation of Ammonia or Hydrazine Derivatives

The dinitrogen (N₂) chemistry of lanthanides remains less developed compared to the d-block metals and lanthanide-promoted N₂ functionalization chemistry in well-defined lanthanide complexes remains elusive. Here we report the synthesis and characterization (SQUID, EPR, DFT, X-Ray) of the siloxide supported heterobimetallic (Tm/K) complexes [{KTm(OSi(O^tBu)₃)₃}₂(μ-η² : η²-N₂)] (1) and [K₃{Tm(OSi(O^tBu)₃)₃}₂(μ-η² : η²-N₂)] (2). Complex 2 provides a rare example of a metal complex of the triply reduced N₂ ^3- radical. The structure of 2 differs from the few previously reported N₂ ^3- complexes as it presents two Tm and three K cations binding the N₂ ^3- radical, facilitating N₂ functionalization. Notably, the K₃Tm₂-bound N₂ ^3- moiety reacts with excess H⁺ to form NH₄Cl in 18 % yield, and with MeOTf at room temperature to yield the dimethyl hydrazido complex [K₂{Tm(OSi(O^tBu)₃)₃}₂(μ-(CH₃)NN(CH₃))] (3). Protonolysis of 3 yields MeHN-NMeH ⋅ 2HCl in 18 % yield.