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 CpLnCl(2)(THF)(3) with two equiv. of Li[N=C(NMe2)(2)] in THF at room temperature affords [Cp(2)Ln(mu-eta(1):eta(2)-L-2)](2) (Ln = Y; L = N-C(NMe2)N-C(NMe2)(2)) and CpLn[N=C(NMe2)(2)](mu-eta(1):eta(2)-L)(2)LnCp(2) (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)(2)C=N](5)Y-3[mu-N=C(NMe2)(2)](2)(mu-eta(1):eta(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.