N-Substituted Guanidinate Anions as Ancillary Ligands in Organolanthanide Chemistry. Synthesis and Characterization of {CyNC[N(SiMe₃)₂]NCy}₂SmCH(SiMe₃)₂

Addition of N(SiMe 3 ) 2 anion equivalents to CyN C NCy provided entry to a series of N-substituted guanidinate complexes of Sm(III) and Yb(III) with the general formula M{CyNC[N(SiMe 3 ) 2 ]NCy} 2 (μ-Cl) 2 Li(S) 2 (M = Sm, Yb; Cy = cyclohexyl; S = Et 2 O, 1 / 2 TMEDA). Substitution of the chloro ligands of these complexes using LiCH(SiMe 3 ) 2 or LiN(SiMe 3 ) 2 yields solvent-free, monomeric alkyl and amido compounds, respectively. Definitive evidence for the molecular structures of these products is provided through single-crystal X-ray analysis, and in particular, the results for Sm{CyNC[N(SiMe 3 ) 2 ]NCy} 2 CH(SiMe 3 ) 2 ( 7 ) and Yb{CyNC[N(SiMe 3 ) 2 ]NCy} 2 N(SiMe 3 ) 2 ( 8 ) are presented. These results provide the first reported example of an organolanthanide complex supported by a guanidinate ligand.