Neutral Fe(iv) alkylidenes, including some that bind dinitrogen

Abstract

Neutral, formally Fe(IV) alkylidene species are sought as plausible olefin metathesis catalysts, and the synthesis of several is described herein. The complexes are prepared via nucleophilic attack (Nu = MeLi, PhCH₂K, 2-picolyllithium, Me₂PCH₂Li, MePhPCH₂Li, Ph₂PCH₂Li) at the imine of cationic [mer-{κ-C,N,C-(C₆H₄-yl)-2-CHN(2-C₆H₄-C(ⁱPr))}Fe(PMe₃)₃][B(3,5-CF₃-C₆H₃)₄]. In contrast, MeMgCl and mesityllithium displaced and deprotonated bound PMe₃, respectively. Structural details are provided for mer-{κ-C,N,C-(C₆H₄-yl)-2-CH(Bn)N(2-C₆H₄-C(ⁱPr))}Fe{trans-(PMe₃)₂}N₂ and {κ-C,N,C,P-(C₆H₄-yl)-2-CH(CH₂PMe₂)N(2-C₆H₄-C(ⁱPr))}Fe(PMe₃)₂.