A Neutral Dy(II) Bis(amide): Synthesis, Magnetism, and a P₄^2– Complex

Reaction of DyCl₃ with KNHAr*, where Ar* = 2,6-Ar₂C₆H₃ and Ar = 2,4,6-ⁱPr₃C₆H₂, results in the formation of ClDy(NHAr*)₂, which can be reduced with KC₈ in THF to room temperature stable dysprosium(II) Dy(NHAr*)₂, where Ar rings of the NHAr* ligand chelate and bind to the metal center to give a black sandwich complex. The redox potential for the reversible Dy^2+/3+-couple was found to be -1.094 ± 0.001 V with respect to FeCp₂^+/0 as 0.000 V. The complex was examined by CASSCF calculations, which suggest the non-Kramer's ion has an 4f⁹5d¹-configuration with little to no <i>s</i>-orbital participation. The reaction of Dy(NHAr*)₂ with CN^tBu results in assumed <i>tert</i>-butyl radical loss along with formation of the isocyanide CN-Dy(NHAr*)₂, which shows a strong absorption in the IR spectrum at 2052 cm^-1 assigned to the C-N stretch. Reaction of P₄ with Dy(NHAr*)₂ gave crystals of salt {Dy(NHAr*)₂}⁺{(P₄)Dy(NHAr*)₂}^-, which shows both η²-P₄^2- and η⁴-P₄^2- ligands in the solid state.