We report the extension of the series of {BIPM TMSH} ？ (BIPM R = C{PPh 2NR} 2, TMS = trimethylsilyl) derived rare earth methanides by the preparation of [Ln(BIPM TMSH)(I) 2(THF)] (Ln = Nd, Gd, Tb), 1a–c, in 34–50% crystalline yields via the reaction of [Ln(I) 3(THF) 3.5] with [Cs(BIPM TMSH)]. Similarly, we have extended the range of {BIPM MesH} ？ (Mes = 2,4,6-trimethylphenyl) derived rare earth methanides with the preparation of [Gd(BIPM MesH)(I) 2(THF) 2], 3, (49%) and [Yb(BIPM MesH)(I) 2(THF)], 4, (26%), via the reaction of [Ln(I) 3(THF) 3.5] with [{K(BIPM MesH)} 2]. Attempts to prepare dysprosium and erbium analogues of 3 or 4 were not successful, with the ion pair species [Ln(BIPM MesH) 2][BIPM MesH] (Ln ？= Dy, Er), 5a–b, isolated in 31–39% yield. The TMEDA ( N', N', N", N"-tetramethylethylenediamine) adducts [Ln(BIPM MesH)(I) 2(TMEDA)] (Ln = La, Gd), 6a–b, were prepared in quantitative yield via the dissolution of [La(BIPM MesH)(I) 2(THF)] or 3 in a TMEDA/THF solution. The reactions of [Ln(BIPM MesH)(I) 2(THF)] [Ln？ = La, Ce, Pr, and Gd ( 3)] or 6a–b with a selection of bases did not afford [La(BIPM Mes)(I)(S) n] (S = solvent) as predicted, but instead led to the isolation of the heteroleptic complexes [Ln(BIPM Mes)(BIPM MesH)] (Ln = La, Ce, Pr and Gd), 7a– d, in low yields due to ligand scrambling.
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