Abstract
Tris(trimethylsilylmethyl) complexes of yttrium and lutetium [LnR(3)(THF)(2)] (R = CH(2)SiMe(3)) were treated with sterically bulky N-heterocyclic carbenes (NHC) 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) and 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes). IPr gave labile mono-adducts [LnR(3)(NHC)], isolated as thermally robust crystals and fully characterized by NMR spectroscopy and X-ray diffraction. IMes gave a similar lutetium mono-adduct [LuR(3)(IMes)] with the lutetium alkyl [LuR(3)(THF)(2)], whereas the yttrium alkyl [YR(3)(THF)(2)] resulted in the formation of an ortho-metalated product. This compound, isolated as a crystalline bis(THF) adduct, contains a strained six-membered chelate ring that has been formed by the C-H bond activation of one of the ortho-methyl groups of the mesityl group. In contrast [LuR(3)(IMes)] only slowly underwent a similar C-H bond activation.
Published Version
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