Synthesis, Structural Characterization, and Reactivity of Mono(amidinate) Rare-Earth-Metal Bis(aminobenzyl) Complexes

Three kinds of solvated lithium amidinates with different coordination models were obtained via recrystallization of [PhC­(NC6H4iPr2-2,6)2]­Li­(THF) (1a) in different solvents. Treatment of o-Me2NC6H4CH2Li with LLnCl2(THF)n (2; L = [PhC­(NC6H4iPr2-2,6)2]− (NCNdipp), [o-Me2NC6H4CH2C­(NC6H4iPr2-2,6)2]− (NCNdipp′)) formed in situ from reaction of LnCl3(THF)x with LLi­(THF) gave the rare-earth-metal bis­(aminobenzyl) complexes LLn­(CH2C6H4NMe2-o)2 (L = NCNdipp, Ln = Sc (3a), Y (3b), Lu (3c); L = NCNdipp′, Ln = Sc (3d), Lu (3e)) in high yields. Reactions of complexes 3 with CO2, PhNCO, 2,6-diisopropylaniline, and S have been explored. CO2 inserted into each Ln–C bond of complexes 3a–c to form the dual-core complexes [(NCNdipp)­Sc­(μ-η1:η1-O2CCH2C6H4NMe2-o)2]2 (4a) and [(NCNdipp)­Ln­(μ-η1:η2-O2CCH2C6H4NMe2-o)­(μ-η1:η1-O2CCH2C6H4NMe2-o)]2 (Ln = Y (4b), Lu (4c)). The reaction of 3b,c,e with PhNCO produced LLu­[OC­(CH2C6H4NMe2-o)­NPh]2(thf) (L = NCNdipp, Ln = Y (5b), Lu (5c); L = NCNdipp′, Ln = Lu (5e)). Protonolysis of 3a,b by 2,6-diisopropylaniline formed straightforwardly the μ2-imido complexes [(NCNdipp)­Ln­(μ-NC6H4iPr2-2,6)]2 (Ln = Sc (6a), Lu (6c)). Reaction of 3e with S8 afforded the sulfur insertion products (NCNdipp′)­Lu­(CH2C6H4NMe2-o)­(SCH2C6H4NMe2-o)­(thf) (7e) and (NCNdipp′)­Lu­(SCH2C6H4NMe2-o)2(thf)2 (7f) in high yields, respectively, depending on the stoichiometric ratio. All of these complexes were fully characterized by elemental analysis, NMR spectroscopy, and X-ray structural determinations.