Reactivity of [Cp*Fe(η⁵‐As₅)] towards Carbenes, Silylenes and Germylenes

Abstract

The reaction behavior of [Cp*Fe(η5‐As5)] (I) (Cp*=C5Me5) towards carbenes and their heavier analogs was investigated. The reaction of I with NHCs (NHCs=N‐heterocyclic carbenes) results in the first substitution products of polyarsenic ligand complexes by NHCs [Cp*Fe(η4‐As5NHC)] (1 a: NHC=IMe=1,3,4,5‐tetramethylimidazolin‐2‐ylidene, 1 b: NHC=IMes=1,3‐bis(2,4,6‐trimethylphenyl)‐imidazolin‐2‐ylidene). In contrast, the reaction of I with EtCAAC (EtCAAC=2,6‐diisopropylphenyl)‐4,4‐diethyl‐2,2‐dimethyl‐pyrrolidin‐5‐ylidene) leads to a fragmentation and the formation of an unprecedented As6‐sawhorse‐type compound [As2(AsEtCAAC)4] (2). The reaction of (LE)2 (L=PhC(NtBu)2; E=Si, Ge) with I resulted in a rearrangement and an insertion of LE fragments, forming unique silicon‐ (4: [Cp*Fe(η4‐As4SiL)], 5 a: [Cp*Fe(η4‐As6SiL)) and germanium‐containing (5 b: [Cp*Fe(η4‐As6GeL)) cyclic polyarsenic ligand complexes.

Applications of low-valent compounds with heavy group-14 elements

“…Treatment of Ge33 with [Cp*Fe(η 5 -As 5 )] led to the formation of Ge48 , which is isostructural to its silicon analog ( Si73b ) (Scheme 187). 180…”