Synthesis of β-diketiminate-ligated bimetallic and monometallic lanthanide amide complexes and their reactivity with isoprene and AlMe3†
Abstract
The amine elimination of lanthanide tris(amide) complexes with the phenylene-bridged bis(β-diketiminate) ligands PARAMe-H2, METAMe-H2 and PARAPr-H2 (PARAMe-H2 = 2[2,6-Me2C6H3NHC(Me)C(H)C(Me)N]-(para-phenylene), METAMe-H2 = 2[2,6-Me2C6H3NHC(Me)C(H)C(Me)N]-(meta-phenylene), PARAPr-H2 = 2[2,6-iPr2C6H3NHC(Me)C(H)C(Me)N]-(para-phenylene)), and the mono-β-diketiminate ligand L2,6-iPr2Ph-H (2,6-iPr2C6H3)NHC(Me)CHC(Me)N(C6H5)) afforded the bimetallic lanthanide amide complexes PARAMe-{Ln[N(SiMe3)2]2}2 (Ln = Y (1), Sm (2)), METAMe-{Y[N(SiMe3)2]2}2 (3), PARAPr-{Ln[N(HSiMe2)2]2}2 (Ln = Y (4), Sm (5)), and the monomeric complexes L2,6-iPr2Ph-Y[N(SiMe3)2]2 (6) and L2,6-iPr2Ph-Y[N(HSiMe2)2]2 (7). In the presence of AlR3 and on activation with 1 equiv. of [Ph3C][B(C6F5)4], complexes 1–7 showed a high activity toward the 1,4-selective polymerization of isoprene. The heterometallic Y/Al methyl complex [L2,6-iPr2Ph]Y[(μ-Me)2AlMe2]2 (8) was prepared to elucidate the real active precursor in the polymerization.