Reduction of dinitrogen to planar bimetallic M2(mu-eta 2:eta 2-N2) complexes of Y, Ho, Tm, and Lu using the K/Ln[N(SiMe3)2]3 reduction system.

The reaction of Ln[N(SiMe3)2]3 with K under N2 in THF forms the dinitrogen complexes {[(Me3Si)2N]2(THF)Ln}2(mu-eta2:eta2-N2) (Ln = Y, Ho, Tm, and Lu) previously available only for lanthanides with highly reducing divalent states, that is, Tm, Dy, and Nd. The Y and Lu complexes are the first diamagnetic complexes of this type. The Ln2N2 moiety is planar, and the 1.268(3) and 1.285(4) A NN distances in these complexes are consistent with the presence of (N2)2-.