N‐tert‐Alkyl‐substituted N‐Heterocyclic Carbenes with a 1,1‘‐Ferrocenediyl Backbone

1,1’-Diaminoferrocene (1) was converted to α-aminonitriles fc[NHC(CN)MeR’]2 (fc=1,1’-ferrocenediyl; 2 a: R’=Me, b: R’=Ph, c: R’=tBu) by reaction with ketones MeC(O)R’ in the presence of NaCN/HOAc or diimine fc(N=CPh2)2 (3) condensation Ph2CO. Treatment a–c 3 MeLi furnished fc(NHR)2 (4 R=tBu, 4 R=CMe2Ph, R=CMe2tBu, d: R=CMePh2) after aqueous work-up. The formylative cyclisation a–d fc[(NR)2CH][BF4] (5H[BF4]) possible only for R=CMe3 (a) and CMe2Ph (b). these formamidinium compounds NaN(SiMe3)2 afforded N-heterocyclic carbenes fc{[N(CMe3)]2C:} (5 a) fc{[N(CMe2Ph)]2C:} b). 5 a thiourea derivative 5aS elemental sulfur. b slowly decompose solution alkene elimination, affording respective formamidine fc(NRCH=N) (6 R=CMe3, 6 R=CMe2Ph). transformed fc{[N(CMe3)][N(CPh3)]CH}[BF4] (5eH[BF4]) Ph3C[BF4].