Triisobutylaluminium-promoted formation of lanthanide hydrides

Abstract

Discrete lanthanide(III) isobutylaluminates Ln[N(SiMe₃)₂](HAliBu₃)(AliBu₄) (Ln = La, Pr, Nd) are obtained from Ln[N(SiMe₃)₂]₃ and triisobutylaluminium (TIBA). Nd[N(SiMe₃)₂](HAliBu₃)(AliBu₄) reacts with crown ether to give the ion pair [Nd(18-c-6){N(SiMe₃)₂}(HAliBu₃)][AliBu₄], featuring a strong Nd–H interaction in the solid state. The equimolar reaction of La[N(SiMe₃)₂](HAliBu₃)(AliBu₄) with fluorene resulted in the concomitant formation of [(μ-fluorenyl)₃La₂(μ-H)(HAliBu₃)₂] and (fluorenyl)₂La[N(SiMe₃)₂]. [(μ-Fluorenyl)₃La₂(μ-H)(HAliBu₃)₂] features fluorenyl ligands with a μ-η⁶:η⁶ coordination around the hydrido-bridged dilanthanum core motif. The reported complexes are the first crystallographically characterized, ancillary ligand-free lanthanide(III) tetraisobutylaluminates, and display potential model systems for Ziegler-type polymerization catalysis.