Synthesis of Dianionic β-Diketiminate Lanthanide Amides L′LnN(SiMe<sub>3</sub>)<sub>2</sub>(THF) by Deprotonation of the β-Diketiminate Ligand L (L = {[(2,6-<i>i</i>Pr<sub>2</sub>C<sub>6</sub>H<sub>3</sub>)NC(CH<sub>3</sub>)]<sub>2</sub>CH}<sup>−</sup>) and the Transformation with [HNEt<sub>3</sub>
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Reaction of β-diketiminate lanthanide dichlorides LLnCl2(THF)2 (L = {[(2,6-iPr2C6H3)NC(CH3)]2CH}−) with 2 equiv of NaN(SiMe3)2 in toluene afforded lanthanide amide complexes supported by a dianionic β-diketiminate ligand L′, L′LnN(SiMe3)2(THF) (L′ ={(2,6-iPr2C6H3)NC(CH2)CHC(CH3)N(2,6-iPr2C6H3)}2–, Ln = Yb (1), Y (2), Gd (3), Sm (4)), in moderate yields via deprotonation of L. Addition of a small amount of THF led to an increase of the yields of 1–4. Lanthanide metals have a great influence on the deprotonation of L. The same reaction with LNdCl2(THF)2 did not afford the analogous complex L′NdN(SiMe3)2(THF), but the normal diamide complex LNd[N(SiMe3)2]2 (5) was isolated instead. The metathesis reaction of the triply bridged dichlorides of Sm, LSmCl(μ-Cl)3SmL(THF), with 2 equiv of NaN(SiMe3)2 yielded the diamide complexes LSm[N(SiMe3)2]2 in toluene, while complex 4 was formed instead in a mixture of toluene and THF. In contrast, the same reactions with LYbCl(μ-Cl)3YbL(THF) either in toluene or in a mixture of toluene and THF both afforded 1. Treatment of 4 with [HNEt3][BPh4] in THF at room temperature gave the novel cationic Sm β-diketiminate amide complex [LSmN(SiMe3)2(THF)2][BPh4] (7) in good yield. Complexes 1–5 and 7 have been confirmed by single-crystal X-ray structural analyses. The mechanism of deprotonation of L was discussed.
