Fluorinated diarylamido complexes of lithium, zirconium, and hafnium

Deprotonation of N-(2-fluorophenyl)-2,6-diisopropylaniline (H (i) PrAr-NF]) with 1 equiv of n-BuLi in toluene at -35 degrees C produced cleanly (i) PrAr-NF]Li. Subsequent recrystallization of (i) PrAr-NF]Li in diethyl ether generated the bis(ether) adduct (i) PrAr-NF]Li(OEt 2) 2. An X-ray study of (i) PrAr-NF]Li(OEt 2) 2 showed it to be a four-coordinate species with the coordination of the fluorine atom to the lithium center. The reactions of (i) PrAr-NF]Li with MCl 4(THF) 2 (M = Zr, Hf), regardless of the stoichiometry employed, afforded the corresponding dichloride complexes (i) PrAr-NF] 2MCl 2 (M = Zr, Hf). Alkylation of (i) PrAr-NF] 2MCl 2 with a variety of Grignard reagents generated (i) PrAr-NF] 2MR 2 (M = Zr, Hf; R = Me, i-Bu, CH 2Ph). The X-ray structures of (i) PrAr-NF] 2ZrCl 2, (i) PrAr-NF] 2HfCl 2, (i) PrAr-NF] 2ZrMe 2, (i) PrAr-NF] 2Zr( i-Bu) 2, and (i) PrAr-NF] 2Hf(CH 2Ph) 2 are all indicative of the coordination of the fluorine atoms to these group 4 metals, leading to a C 2-symmetric, distorted octahedral geometry for these molecules.