A Stable Crystalline N‐Heterocyclic Carbene with a 1,1’‐Ferrocenylene Backbone and Benzylic <i>N</i>‐Substituents

Abstract Two ferrocene‐based NHCs of the type fc[(NR) 2 C:] ( 1 R ; fc=1,1’‐ferrocenylene) containing benzylic N ‐substituents were synthesised from corresponding formamidinium compounds H[BF 4 ] by reaction with LiN(SiMe 3 ) . In case R=CH Ph (Bn), carbene was characterised through trapping reactions sulfur and selenium, which afforded fc[(NBn) CS] Bn S) CSe] Se), respectively. A thermally stable obtained Mes (Bn*). Its selenium fc[(NBn*) Bn* [Rh(μ‐Cl)(COD)] (COD=cycloocta‐1,5‐diene), followed substitution COD ligand CO, furnished cis ‐[RhCl(CO) )]. combination IR data )], NMR ], Se indicate that is substantially more nucleophilic electrophilic than conventional Arduengo carbenes, exhibiting an ambiphilicity similar to CAACs. The crystal structures salts HX (X=[BF R=Bn, Bn*; X=Cl, R=Bn*), its Au I complex [AuCl( )] as well derivatives E (E=S, Se; Bn*), Rh complexes (R=Bn, Bn*) Cu [CuBr( determined single‐crystal X‐ray diffraction (XRD). addition, crystals diimine fc(N=CHMes) diamine fc(NHBn*) also XRD.