Two ferrocene-based NHCs of the type fc[(NR)₂C:] (1ᴿ; fc=1,1’-ferrocenylene) containing benzylic N-substituents were synthesised from the corresponding formamidinium compounds 1ᴿH[BF₄] by reaction with LiN(SiMe₃)₂. In the case of R=CH₂Ph (Bn), the carbene was characterised through trapping reactions with sulfur and selenium, which afforded fc[(NBn)₂CS] (1ᴮⁿS) and fc[(NBn)₂CSe] (1ᴮⁿSe), respectively. A thermally stable carbene was obtained with R=CH₂Mes (Bn*). Its reaction with sulfur and selenium afforded fc[(NBn*)₂CS] (1ᴮⁿS) and fc[(NBn)₂CSe] (1ᴮⁿSe), respectively. Its reaction with [Rh(μ-Cl)(COD)]₂ (COD=cycloocta-1,5-diene), followed by substitution of the COD ligand by CO, furnished cis-[RhCl(CO)₂(1ᴮⁿ)]. In combination with IR data of cis-[RhCl(CO)₂(1ᴮⁿ*)], NMR data of 1ᴮⁿH[BF₄], 1ᴮⁿ and 1ᴮⁿSe indicate that 1ᴮⁿ is substantially more nucleophilic and more electrophilic than conventional Arduengo carbenes, exhibiting an ambiphilicity similar to that of CAACs. The crystal structures of the formamidinium salts 1ᴿHX (X=[BF₄], R=Bn, Bn*; X=Cl, R=Bn*), of the carbene 1ᴮⁿ* and its Auˡ complex [AuCl(1ᴮⁿ*)] as well as of the sulfur and selenium derivatives 1ᴿE (E=S, Se; R=Bn, Bn*), the Rhˡ complexes cis-[RhCl(CO)₂(1ᴿ)] (R=Bn, Bn*) and the Cuˡ complex [CuBr(1ᴮⁿ)] were determined by single-crystal X-ray diffraction (XRD). In addition, the crystals structures of the diimine fc(N=CHMes)₂ and the diamine fc(NHBn*)₂ were also determined by XRD.
@article{doi:10.17170/kobra-202303067575,
author ={Zinke, Julian and Bruhn, Clemens and Siemeling, Ulrich},
title ={A Stable Crystalline N-Heterocyclic Carbene with a 1,1’ - Ferrocenylene Backbone and Benzylic N-Substituents},
keywords ={540 and Carbene and Chemie},
copyright ={http://creativecommons.org/licenses/by/4.0/},
language ={en},
journal ={Zeitschrift für anorganische und allgemeine Chemie : ZAAC = Journal of inorganic and general chemistry},
year ={2022-12-08}
}