The liquid hydrogen chloride solvent system. Part XIV. Reactions of π-cyclopentadienyldicarbonyliron dimer, of π-cyclopentadienylirondicarbonyl chloride, bromide, and iodide, and of π-cyclopentadienyltricarbonyliron chloride in the solvent

Abstract

π-Cyclopentadienyldicarbonyliron dimer is monobasic in liquid hydrogen chloride, giving the [(π-C₅H₅)Fe-(CO)₂]₂H⁺ ion. Spectroscopic evidence (Mössbauer, ¹H n.m.r., and i.r.) shows that this ion contains two (π-C₅H₅)-Fe(CO)₂ units linked by a symmetric Fe–H–Fe bridge. Reaction of a solution of the dimer with nitrosyl chloride or chlorine gives mixtures containing π-cyclopentadienyldicarbonyliron chloride. π-Cyclopentadienyldicarbonyliron chloride is a base in the solvent forming [(π-C₅H₅)Fe(CO)₂]₂Cl⁺BCl₄^– on treatment with boron trichloride. π-Cyclopentadienyltricarbonyliron chloride also acts as a base in the solvent giving (π-C₅H₅)Fe(CO)₃⁺BCl₄^–with boron trichloride.