Synthesis and Structures of Zirconium and Hafnium Alkyl Complexes That Contain [H3CC(2-C5H4N)(CH2NAr)2]2- ([ArNpy]2-; Ar = Mesityl, Triisopropylphenyl) Ligands

We report the synthesis of the arylated diamidopyridine ligands [H 3 CC(2-C 5 H 4 N)(CH 2 NAr) 2 ] 2 - ([ArNpy] 2 -; Ar = 2,4,6-Me 3 C 6 H 2 (Mes), 2,4,6-(i-Pr) 3 C 6 H 2 (Trip)). [ArNpy]M(NMe 2 ) 2 (M = Zr, Hf) complexes were prepared by treating M(NMe 2 ) 4 with H 2 [ArNpy], while [ArNpy]MCl 2 was prepared in a reaction between [ArNpy]M(NMe 2 ) 2 and Me 3 SiCl. Zirconium dialkyl complexes that were prepared include [MesNpy]ZrR 2 (R = methyl, benzyl, neopentyl, isobutyl), [MesNpy]Zr(THF)Me 2, [Li(Et 2 O)]{[MesNpy]ZrMe 3 }, and [TripNpy]Zr(i-Bu) 2 . Hafnium [MesNpy]HfR 2 complexes are relatively stable, even when β-protons are present in R (R = Me, Et, n-Pr, n-Bu, i-Bu, i-Pr). Monoalkyl monochloro hafnium complexes that were prepared include [MesNpy]Hf(i-Pr)Cl and [MesNpy]Hf(t-Bu)Cl. X-ray studies were carried out for [MesNpy]ZrMe 2, [MesNpy]Zr(THF)Me 2, [Li(Et 2 O)]{[MesNpy]ZrMe 3 }, [TripNpy]Zr(i-Bu) 2, [MesNpy]Hf(i-Pr)Cl, and [MesNpy]Hf(i-Pr) 2 .