The chemistry of phosphorus–fluorine compounds. Part VIII. Synthesis and nuclear magnetic resonance spectra of tetrakisfluorophosphine derivatives of zerovalent nickel

Abstract

Fluorophosphine complexes of zerovalent nickel of the type NiL₄[where L = PF₃, CF₃PF₂, (CF₃)₂PF, CCl₃PF₂,Et₂NPF₂, and C₅H₁₀NPF₂] are readily synthesised by the reaction between nickelocene and the fluorophosphine, often under very mild conditions. This synthetic approach avoids difficulties encountered in displacement reactions using nickel tetracarbonyl which invariably lead to NiL_n(CO)_4–n mixtures. The i.r. and ¹H- and ¹⁹F-n.m.r. spectra of the complexes are presented and unusual features of the latter are discussed. A significant low-field chemical shift (–17 to –59 p.p.m.) of the fluorine atoms directly bonded to phosphorus, which occurs on complex formation, is attributed to the availability of low-lying excited states in the phosphorus–nickel bonds.