Fluorinated Diarylamido Complexes of Lithium, Zirconium, and Hafnium

Deprotonation of N-(2-fluorophenyl)-2,6-diisopropylaniline (H[iPrAr-NF]) with 1 equiv of n-BuLi in toluene at –35 °C produced cleanly [iPrAr-NF]Li. Subsequent recrystallization of [iPrAr-NF]Li in diethyl ether generated the bis(ether) adduct [iPrAr-NF]Li(OEt2)2. An X-ray study of [iPrAr-NF]Li(OEt2)2 showed it to be a four-coordinate species with the coordination of the fluorine atom to the lithium center. The reactions of [iPrAr-NF]Li with MCl4(THF)2 (M = Zr, Hf), regardless of the stoichiometry employed, afforded the corresponding dichloride complexes [iPrAr-NF]2MCl2 (M = Zr, Hf). Alkylation of [iPrAr-NF]2MCl2 with a variety of Grignard reagents generated [iPrAr-NF]2MR2 (M = Zr, Hf; R = Me, i-Bu, CH2Ph). The X-ray structures of [iPrAr-NF]2ZrCl2, [iPrAr-NF]2HfCl2, [iPrAr-NF]2ZrMe2, [iPrAr-NF]2Zr(i-Bu)2, and [iPrAr-NF]2Hf(CH2Ph)2 are all indicative of the coordination of the fluorine atoms to these group 4 metals, leading to a C2-symmetric, distorted octahedral geometry for these molecules.