Schädle, Dorothea, Litlabø, Rannveig, Meermann-Zimmermann, Melanie, Thim-Spöring, Renita, Schädle, Christoph, Maichle-Mössmer, Cäcilia, Törnroos, Karl W., and Anwander, Reiner
Homoleptic tetramethylaluminates Ln(AlMe4)3react with KTptBu,Me(TptBu,Me= tris(3-tBu-5-Me-pyrazolyl)borato) to yield rare-earth-metal methylidene complexes (TptBu,Me)Ln(μ3-CH2)[(μ-Me)AlMe2]2(Ln = La, Ce, Nd). The lanthanum reaction is prone to additional C–H- and B–N-bond activation, affording coproducts La[HB(pzMe,tBu)(pzCMe2,Me)2][(μ-CH2)(μ-Me)AlMe2]2and [La(μ-pztBu,Me)(AlMe4)2]2(pztBu,Me= 3-tBu-5-Me-pyrazolato). The protonolysis reaction of Ln(AlMe4)3and HpztBu,Meprovides more efficient access to [Ln(μ-pztBu,Me)(AlMe4)2]2(Ln = La, Nd). Treatment of Ln(AlMe4)3with KTpMe,Meled to methylidene complexes (TpMe,Me)Ln(μ3-CH2)[(μ-Me)AlMe2]2(Ln = Nd, Sm) or bis(tetramethylaluminate) complexes (TpMe,Me)Ln(AlMe4)2(Ln = Y, Lu). The neodymium reaction generated methine derivative (TpMe,Me)Nd[(μ4-CH)(AlMe2)2(μ-pz,Me,Me)][(μ-Me)AlMe2] as a minor coproduct. The reaction of Ln(GaMe4)3(Ln = Y, La, Ce, Nd, Sm, Ho) with HTptBu,Megave methylidene complexes (TptBu,Me)Ln(μ3-CH2)[(μ-Me)GaMe2]2(Ln = La, Ce, Nd, Sm) and alkyl complexes (TptBu,Me)LnMe[(μ-Me)GaMe3] (Ln = Y, Ho), while competing B–N bond activation reactions produced GaMe2[BH(Me)(μ-pztBu,Me)2] and (TptBu,Me)Ln(η2-pztBu,Me)[(μ-Me)GaMe3] (Ln = Y, Ho). The steric impact of the TpR,Meligands was examined by cone angle calculations. Rare-earth-metal methylidene complexes (TptBu,Me)Ln(μ3-CH2)[(μ-Me)EMe2]2(E = Al, Ga) successfully promote carbonyl methylenation reactions upon addition of ketone.