Expanding Divalent Organolanthanide Chemistry: The First Organothulium(II) Complex and the In Situ Organodysprosium(II) Reduction of Dinitrogen We thank the US National Science Foundation for support of this research.

The right choice of solvents, ligand ([C5H3(SiMe3)2]−), and reaction conditions has facilitated the isolation and structural characterization of the first TmII metallocene (see picture). In situ organometallic chemistry of the even more reducing DyII ion, namely a dinitrogen reduction to give the DyIII dinitrogen complex [{[C5H3(SiMe3)2]2Dy}2N2], reveals the importance of carrying out such reactions in an atmosphere more inert than nitrogen.