Synthesis, Reactivity, and Structure of Mixed-Ligand Ytterbium Complexes Supported by β-Diketiminate

The preparation and reaction chemistry of β-diketiminate ytterbium complexes is described. Reaction of [(DIPPh)2nacnac]Li ((DIPPh)2nacnac = N,N-diisopropylphenyl-2,4-pentanediimine anion) with 1 equiv of anhydrous YbCl3 in THF, followed by crystallization from toluene, affords the monomeric complex [(DIPPh)2nacnac]YbCl2(THF)2 (1) in high yield. Recrystallization of complex 1 from toluene gives an unexpected dimeric complex, {[(DIPPh)2nacnac]YbCl(μ-Cl)3Yb[(DIPPh)2nacnac](THF)}·1/2MePh (2), which has a rare triple chloride bridge. Reaction of complex 1 with CH3C5H4Na in 1:1 molar ratio in THF gives the mixed-ligand ytterbium chloride (CH3C5H4)[(DIPPh)2nacnac]YbCl (3). Complex 3 readily undergoes metathesis reactions with 1 equiv of LiNPh2 or LiNPri 2 in THF to form the compounds (CH3C5H4)[(DIPPh)2nacnac]YbNPh2 (4) and (CH3C5H4)[(DIPPh)2nacnac]YbNPri 2 (5), respectively. The complexes 2, 3, and 4 have been characterized by an X-ray diffraction structure determination.