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 remainsless developed compared to the d-block metals and lanthanide-promoted N2 functionalization chemistry in well-defined lanthanidecomplexes remains elusive. Here we report the synthesis andcharacterization (SQUID, EPR, DFT, X-Ray) of the siloxidesupported heterobimetallic (Tm/K) complexes[{KTm(OSi(OtBu)3)3}2(μ-η2:η2-N2)] (1) and [K3{Tm(OSi(OtBu)3)3}2(μ-η2:η2-N2)] (2). Complex 2 provides a rare example of a metalcomplex of the triply reduced N23- radical. The structure of 2 differsfrom the few previously reported N23- complexes as it presents twoTm and three K cations binding the N23- radical, facilitating N2functionalization. Notably, the K3Tm2-bound N23- moiety reacts withexcess H+ to form NH4Cl in 18% yield, and with MeOTf at roomtemperature to yield the dimethyl hydrazido complex[K2{Tm(OSi(OtBu)3)3}2(μ-(CH3)NN(CH3))] (3). Protonolysis of 3yields MeHN-NMeH·2HCl in 18 % yield.