Synthesis and reactivity of novel organo main group and rare earth metal complexes

An ambiphilic bis(oxazolinyl)borane proligand and zinc dialkyls react via alkyl group transfer or β-hydrogen abstraction. Both alkyl abstraction and β-hydrogen abstraction processes can be observed, and products vary with coordinating solvent or non-coordinating solvent. We interpret this by proposing that the latter process is favoured by formation of a bis(oxazolinyl)borane-zinc adduct that positions a β-hydrogen in the proximity of the Lewis acid center. Rare earth benzyl complexes {MeC(C5Me4)(OxMe2)2}Ln(CH2Ph) (Ln = Sc, Lu, Y) are prepared in high yield by reactions between Ln(CH2Ph)3(THF)3 and the H{MeC(C5Me4)(OxMe2)2} ligand. These compounds are precursors for the first examples of terminal lutetium and yttrium imidoborate complexes. {MeC(C5Me4)(OxMe2)2}Lu=NHB(C6F5)3 and {MeC(C5Me4)(OxMe2)2}Y=NHB(C6F5)3 are synthesized by the reaction of NH3.B(C6F5)3 with {MeC(C5Me4)(OxMe2)2}Ln(CH2Ph)2 complexes (Ln = Lu, Y). These compounds are also precursors for the first examples of terminal lutetium and yttrium imido complexes containing β-CH. Reactions between one equivalent of benzylic amines NH2CH2(Aryl) and {MeC(C5Me4)(OxMe2)2}Ln(CH2Ph)2 give imido complexes {MeC(C5Me4)(OxMe2)2}Lu=NCH2Ar and {MeC(C5Me4)(OxMe2)2}Y=NCH2Ar. β-CH agostic interactions are observed to stabilize these imido complexes. Bisamide complexes {MeC(C5Me4)(OxMe2)2}Ln(NHCH2Ar)2 are formed by the reaction of two equivalent of NH2CH2Ar amine and {MeC(C5Me4)(OxMe2)2}Ln(CH2Ph)2 complexes