Room temperature C-N bond cleavage of anionic guanidinate ligand in rare-earth metal complexes.

The dissociation of the anionic guanidinate ligand N=C(NMe2)2 promoted by rare-earth metal complexes at room temperature is described. Treatment of CpLnCl2(THF)3 with two equiv. of Li[N=C(NMe2)2] in THF at room temperature affords [Cp2Ln(μ-η(1):η(2)-L2)]2 (Ln = Y; L = N=C(NMe2)N=C(NMe2)2) and CpLnN=C(NMe2)22LnCp2 (Ln = Dy) in moderated yields, respectively. YCl3 reacts with three equiv. of Li[N=C(NMe2)2] under the same conditions to give a trinuclear yttrium guanidinate [(Me2N)2C=N]5Y3[μ-N=C(NMe2)2]2(μ-η(1):η(2)-L)2 in 63% yield. These reactions show that rare-earth metals can promote a C-N bond cleavage of the guanidine anion N=C(NMe2)2 at room temperature. All new complexes were characterized by elemental analysis and spectroscopic properties, and their solid-state structures were determined through single-crystal X-ray diffraction analysis.