Reactivity of Rare-Earth Metal Complexes Stabilized by an Anilido-Phosphinimine Ligand

Treatment of anilido-phosphinimine-ligated yttrium mono(alkyl) complex 1a, LY(CH2Si(CH3)3)(THF) (L = o-(2,6-C6H3iPr2)NC6H4P(C6H4)(C6H5)N(2,4,6-C6H2Me3)), with 2 equiv of phenylsilane in DME afforded methoxy-bridged complex 2, [LY(μ-OCH3)]2, via the corresponding hydrido intermediate. When excess isoprene was added to the mixture of 1a and phenylsilane, a η3-isopentene product, 3, LY(CH2C(CH3)CHCH3)(THF), was isolated. A lutetium chloride, LLuCl(DME) (4), was generated through the reaction of lutetium mono(alkyl) complex 1b, LLu(CH2Si(CH3)3)(THF), with [Ph3C][B(C6F5)4]·LiCl accompanied by the formation of [Li(DME)3]+[B(C6F5)4]−. Metathesis reaction of 1b with excess AlMe3 at room temperature gave a methyl-terminated counterpart, 5, LLu(CH3)(THF)2. In all these reactions, the Ln−Cphenyl bonds of complexes 1 remained untouched. However, protonolysis of complex 1b with 2 equiv of phenylacetylene in DME provided a lutetium bis(acetylide), LHLu(CCPh)2(DME) (6), and the linkage of the Ln−Cphenyl bond was cleaved, indicating that the activated C−H bond was recovered.