CH bond activation of methane by a transient η2-cyclopropene/metallabicyclobutane complex of niobium

Chen Li (1, 2) , Chiara Dinoi (2, 1) , Yannick Coppel (2) , Michel Etienne (2)

1 LPCNO - Laboratoire de physique et chimie des nano-objets
2 LCC - Laboratoire de chimie de coordination

This study challenges the problem of the activation of a CH bond of methane by soluble transition metal complexes. High pressure solution NMR, isotopic labeling studies, and kinetic analyses of the degenerate exchange of methane in the methyl complex [TpMe2NbCH3(c-C3H5)(MeCCMe)] (1) are reported. Stoichiometric methane activation by the mesitylene complex [TpMe2Nb(CH2-3,5-C6H3Me2)(c-C3H5) (MeCCMe)] (2) giving 1 is also realized. Evidence is provided that these reactions proceed via an intramolecular abstraction of a β-H of the cyclopropyl group to form either methane or mesitylene from 1 or 2, respectively, yielding the transient unsaturated η2-cyclopropene/metallabicyclobutane intermediate [TpMe2Nb(η2-c-C3H4) (MeCCMe)] A. This is followed by its mechanistic reverse 1,3-CH bond addition of methane yielding the product.

Domaines: Chimie de coordination

Chen Li, Chiara Dinoi, Yannick Coppel, Michel Etienne. CH bond activation of methane by a transient η2-cyclopropene/metallabicyclobutane complex of niobium. Journal of the American Chemical Society, 2015, 137 (39), pp.12450-12453. ⟨10.1021/jacs.5b07859⟩. ⟨hal-01916805⟩