Trivalent Rare-Earth-Metal Bis(trimethylsilyl)amide Halide Complexes by Targeted Oxidations.

In contrast to previously applied salt metathesis protocols the targeted rare-earth-metal compounds LnN(SiMe) were accessed by oxidation of Ln(II) silylamide precursors. Treatment of SmN(SiMe) with 0.5 equiv of CCl or 0.25 equiv of TeBr in thf and crystallization thereof gave [Sm{N(SiMe)}(μ-X)(thf)] (X = Cl, Br). A similar reaction/crystallization procedure performed with 0.5 equiv of 1,2-diiodoethane gave monomeric Sm[N(SiMe)]I(thf). Switching to YbN(SiMe), the aforementioned oxidants generated monomeric five-coordinate complexes Yb[N(SiMe)]X(thf) (X = Cl, Br, I). The reaction of EuN(SiMe) with 0.5 equiv of CCl in thf yielded the separated ion pair [Eu{N(SiMe)}Cl][(thf)Eu(μ-Cl)Eu(thf)]. Performing the chlorination in n-hexane led to oxidation followed by rapid disproportionation into EuCl(thf) and Eu[N(SiMe)]. The bromination reaction did not afford crystalline material, while the iodination gave crystals of divalent EuI(thf). Use of trityl chloride (PhCCl) as the oxidant in thf accomplished the Eu(III) species [Eu{N(SiMe)}(μ-Cl)(thf)]. In situ oxidation of putative [Tm{N(SiMe)}(thf) ] using 0.5 equiv of CCl in thf followed by crystallization from n-hexane led to the formation of a mixture of [Tm{N(SiMe)}(μ-Cl)(thf)] and Tm[N(SiMe)]. Switching the oxidant to 0.5 equiv of 1,2-diiodoethane and crystallizing from thf repeatedly afforded the bis-halogenated complex Tm[N(SiMe)]I(thf).