Reactive Dimerization of an N‐Heterocyclic Plumbylene: C−H Activation with PbII

Leaded ferrocene: An N‐heterocyclic plumbylene with a ferrocenylene backbone undergoes an unprecedented type of dimerization. The formation of an aggregation dimer is followed by an intramolecular electrophilic substitution by the endo attack of a Pb^II atom with the cleavage of a C−H bond and formation of a Pb−C and an N−H bond (see scheme). The reaction affords a planar‐chiral ferrocene derivative and introduces the concept of C−H activation with Pb^II.

Abstract

The N‐heterocyclic plumbylene [Fe{(η⁵‐C₅H₄)NSiMe₃}₂Pb:] is in equilibrium with an unprecedented dimer in solution, whose formation involves the cleavage of a strong C−H bond and concomitant formation of a Pb−C and an N−H bond. According to a mechanistic DFT assessment, dimer formation does not involve direct Pb^II insertion into a cyclopentadienyl C−H bond, but is best described as an electrophilic substitution. The bulkier plumbylene [Fe{(η⁵‐C₅H₄)NSitBuMe₂}₂Pb:] shows no dimerization, but compensates its electrophilicity by the formation of an intramolecular Fe−Pb bond.

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