A Transient Iron Carbide Generated by Cyaphide Cleavage.

Despite their potential relevance as molecular models for industrial and biological catalysis, well-defined mononuclear iron carbide complexes are unknown, in part due to the limited number of appropriate C synthons. Here, we show the ability of the cyaphide anion (C≡P) to serve as a C source. The high spin ( = 2) cyaphide complex PhB(BuIm)Fe-C≡P (PhB(BuIm) = phenyl(tris(3--butylimidazol-2-ylidene)borate) is readily accessed using the new cyaphide transfer reagent [Mg(NacNac)(CP)] (NacNac = CH{C(CH)N(Dipp)} and Dipp = 2,6-di(iso-propyl)phenyl).

Trimethylsilyldiazomethane Disassembly at a Three-Fold Symmetric Iron Site.

The reaction of equimolar trimethylsilyldiazomethyllithium (LiTMSD) with high spin ( = 2) PhB(AdIm)FeCl (PhB(AdIm) = tris(3-adamantylimidazol-2-ylidene)phenylborate) affords the corresponding nitrilimido complex PhB(AdIm)Fe-N═N═C(SiMe). This complex can be converted to the thermodynamically more favorable -isocyanoamido isomer PhB(AdIm)Fe-C═N═N(SiMe) by reaction with an additional equivalent of LiTMSD. While the iron(II) complexes are four-coordinate, the diazomethane is bound side-on in the iron(I) congener PhB(AdIm)Fe(,'-κ-NC(H)Si(CH)).