Monoalkyllanthanide Complexes with New β-Diketiminato Derivative Dianionic Ligands

A new class of β-diketiminato derivative dianionic ligands was designed, and three ligand precursors [CH 3 C(ArN H )CHC(CH 3 )(NCH 2 CH 2 -N H R)] (Ar = 2,6-( i Pr) 2 C 6 H 3; R = t Bu ( H 2 L1 ), 2,6-(CH 3 ) 2 C 6 H 3 ( H 2 L2 ), 2,6-( i Pr) 2 C 6 H 3 ( H 2 L3 )) were synthesized. The alkane elimination reactions between these ligand precursors and Ln(CH 2 SiMe 3 ) 3 (THF) n provided eight five-coordinate monoalkyllanthanide complexes, in which the ligand serves as a tridentate dianionic donor, with one −CH 2 SiMe 3 and one THF molecule completing the five-coordinate center. These monoalkyl complexes exhibited low to very high catalytic activities for intramolecular hydroamination of 2,2-dimethyl-1-aminopent-4-ene. The catalytic activity increased with increasing metal ion size. For the Nd complex, 98% yield was obtained in 1 h at 60 °C with 0.5 mol % catalyst loading.