Komplexchemie perhalogenierter Cyclopentadiene und Alkine, Teil 31 [1]. Darstellung von 2,3-Dichlor- und 2,3,4-Trichlor-1-(2-pyridyl)ferrocen [CpFe{C5H2-nCl2+n(2-C5H4N)}] (n=0, 1). Molekülstrukturen von [Cpe{C5HCl3(2-C5H4N)}] und {C5HCl2(PPh3)(2-C5H4N)g, einem unerwarteten Nebenprodukt / Coordination Chemistry of Perhalogenated Cyclopentadienes and Alkynes, Part 31. Synthesis of 2,3-Dichloro- and 2,3,4-Trichloro-1-(2-pyridyl)ferrocene [CpFe{C5H2-nCl2+n(2-C5H4N)}] (n=0, 1). Molecular Structures of [CpFe{C5HCl3(2-C5H4N)}] and {C5HCl2(PPh3)(2-C5H4N)}, an Unexpected Side Product

Abstract

Lithiation of 1,2-dichloro- or 1,2,3-trichloroferrocene with lithium tetramethylpiperidinide, followed by transmetallation with ZnCl2 and Pd(II)-catalyzed coupling with 2-bromopyridine, yield the pyridylferrocenes [CpFe{C5H2-nCl2+n(2-C5H4N)}] (2a, b, n=0 or 1) as brown oils of low stability. Recrystallization of 2b produced a small number of X-ray quality crystals, which could be shown to have the proposed constitution. However, from the recrystallization solution of 2a a few crystals precipitated whose X-ray structure determination identified them as a metal-free phosphonium ylide {C5HCl2(2-C5H4N)(PPh3)} (3)