On the Way to N‐Heterocyclic Silylenes with a 1,1′‐Ferrocenediyl Backbone: Synthesis and Structures of Silicon(IV) Compounds of the Type [Fe{(η5‐C5H4)NR}2SiX2

Abstract

Potential precursors for the synthesis of ferrocene‐based N‐heterocyclic silylenes of the type [Fe{(η5‐C5H4)NR}2Si:] (1Si) were investigated. The silicon(IV) dibromides 1aSiBr2 – 1cSiBr2 [a: R = SiMe3, b: R = CH2CMe3, c: R = 3,5‐(CF3)2‐C6H3] as well as the dichlorides 1aSiCl2 and 1bSiCl2 were prepared in high yield. Attempts to synthesize the target silylenes from these silicon(IV) dihalides by reductive methods failed. Strong reducing agent like alkali metals or KC8 only afforded intractable mixtures. No reaction was observed with a range of milder reducing agents. 1aSiHCl and 1bSiHCl were synthesized in good yields as alternative potential silylene precusors. Their dehydrochlorination was attempted with a wide variety of strong bases, but failed due to inertness. The crystal structures of the new silicon(IV) halides were determined by single‐crystal X‐ray diffraction, with the exception of 1bSiHCl. 1aSiH2 and 1bSi(NH2)2 were also synthesized and structurally characterized.