Palladium(II)-induced preferential activation of the σ[Csp2(phenyl)–Cl] bond versusσ[Csp2(ferrocene)–H]. Crystal structure of [Fe(η5-C5H5){η5-C5H4CH2NCH(C6H3Cl2-2,6)}]

Abstract

The ferrocenylimine [Fe(η⁵-C₅H₅){η⁵-C₅H₄CH₂NCH(C₆H₃Cl₂-2,6)}] has been prepared by condensation of aminomethylferrocene and 2,6-dichlorobenzaldehyde, and characterized by IR, NMR (¹H and ¹³C) spectroscopy and X-ray diffraction. The compound is triclinic, space group P, with a= 7.553(3), b= 11.763(2), c= 18.148(2)Å, α= 89.94(1), β= 98.90(2) and γ= 91.91(2)°. It reacts with Na₂[PdCl₄] and NaO₂CMe·3H₂O in a 1 : 1 : 1 molar ratio, producing the di-µ-chloro-bridged cyclopalladated complex [{[graphic omitted]CH₂(η⁵-C₅H₄)Fe(η⁵-C₅H₅)](µ-Cl)}₂]. Further treatment of this compound with triphenylphosphine results in cleavage of the ‘Pd(µ-Cl)₂Pd’ units, yielding the monomeric derivative [[graphic omitted]CH₂(η⁵-C₅H₄)Fe(η⁵-C₅H₅)}Cl(PPh ₃)]. These compounds contain an endocyclic five-membered palladocycle fused with the phenyl ring and arise by activation of a σ(C–Cl) bond. The reactivity of N-(2,6-dichlorobenzylidene)benzylamine and the analogous ferrocenyl Schiff bases is compared.