Selective Intermolecular C–H Bond Activation: A Straightforward Synthetic Approach to Heteroalkyl Yttrium Complexes Containing a Bis(pyrazolyl)methyl Ligand

The reactions of bis(pyrazolyl)methanes CH2(C3HN2R2-3,5)2 (R = Me, tBu) with Y(CH2SiMe3)3(THF)2 and LY(CH2SiMe3)2(THF)n (L = amidopyridinate (Ap′), amidinate (Amd), tridentate amidinate bearing 2-methoxyphenyl pendant in a side arm (AmdOMe) and pentamethylcyclopentadienyl (Cp*); n = 0, 1) were investigated. CH2(C3HN2tBu2-3,5)2 turned out to be inert in these reactions, while less bulky CH2(C3HN2Me2-3,5)2 easily undergoes metalation by yttrium alkyls. The reaction of Y(CH2SiMe3)3(THF)2 with CH2(C3HN2Me2-3,5)2 regardless of the molar ratio of the reagents affords a homoleptic tris(alkyl) species, Y[CH(C3HN2Me2-3,5)2]3 (1). However, the reactions of equimolar amounts of LY(CH2SiMe3)2(THF)n and CH2(C3HN2Me2-3,5)2 occur selectively with replacement of a sole CH2SiMe3 fragment and afford the related heteroalkyl complexes LY(CH2SiMe3)[CH(C3HN2Me2-3,5)2](THF)n (L = Ap′, n = 1 (6); Amd, n = 0 (7); AmdOMe, n = 1 (8); Cp*, n = 1 (9)) in good yields. The second equivalent of CH2(C3HN2Me2-3,5)2 does not react with het...