The synthesis, structure and reactivity of 4-nonafluorobiphenyl complexes

Abstract

The Grignard reagent Ar_F′MgBr (Ar_F′ = 4-(C₆F₅)C₆F₄) reacts with Me₃SiCl, Me₂SiCl₂ and Me₃SnCl to give the 4-nonafluorobiphenyl group 14 complexes Ar_F′Me₃Si, (Ar_F′)₂Me₂Si and Ar_F′Me₃Sn respectively. Ar_F′Me₃Sn undergoes only methyl group exchange when treated with BBr₃, yielding Ar_F′Me₂SnBr. The solid state structures of Ar_F′Me₃Sn and Ar_F′Me₂SnBr have been determined and exhibit the expected distorted tetrahedral geometries at tin. The reaction between three equivalents of Ar_F′MgBr and BF₃ was not selective, while one equivalent of Ar_F′MgBr and (Ar_F)₂BF (Ar_F = C₆F₅) reacted cleanly to give (Ar_F)₂Ar_F′B. Treatment of BCl₃ with three equivalents of Ar_F′Li, prepared at low temperature from the reaction between Ar_F′Br and n-BuLi, yielded (Ar_F′)₃B. The molecular structures of the acetonitrile adducts of (Ar_F)₂Ar_F′B and (Ar_F′)₃B closely resemble that of (Ar_F)₃B·NCMe. During the course of the boron investigations, reaction with adventitious water led to the structural characterization of (Ar_F′)₂BOH·OH₂ as a hydrogen-bonded dimer. The Grignard reagent reacts selectively with ZnCl₂ in diethyl ether giving first [(Ar_F′)Zn(μ-Cl)(OEt₂)]₂ then (Ar_F′)₂Zn(OEt₂)₂, both of which have been characterised by X-ray diffraction. The corresponding reaction with HgCl₂ requires the use of tetrahydrofuran as the solvent and yields (Ar_F′)₂Hg(THF)₂.