Reactions of Bromoacetylene with Primary Amine on a Butterfly-Type Tetrairon Core to Give Isonitrile and Methyne through Oxidation and Deprotonation

Reaction of [(η5-C5H4Me)4Fe4(HCCH)(HCC–Br)](PF6) with tBuNH2 forms [(η5-C5H4Me)4Fe4(HCCH)(HCC–NHtBu)](PF6), of which one electron oxidation leads to carbon–carbon bond cleavage to give [(η5-C5H4Me)4Fe4(HCCH)(μ3-CH)(μ3-CNHtBu)](PF6)2, and further treatment with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) affords [(η5-C5H4Me)4Fe4(HCCH)(μ3-CH)(μ3-η1-CNtBu)](PF6). Thus, the HCCBr group is converted to tBuNC and CH groups on the redox-responsive tetrairon core.