Divergent Fe-Mediated C–H Activation Paths Driven by Alkali Cations

The association of the ferrous complex FeIICl2(dmpe)2 (1) with alkali bases
M(hmds) (M
= Li, Na, K) proves to be an efficient platform for the activation
of Ar–H bonds. Two mechanisms can be observed, leading to either
Ar–FeII species by deprotonative ferration or hydrido
species Ar–FeII–H by oxidative addition of
transient Fe0(dmpe)2 generated by reduction
of 1. Importantly, the nature of the alkali cation in
M(hmds) has a strong influence on the preferred path. Starting from
the same iron precursor, diverse catalytic applications can be explored
by a simple modulation of the MI cation. Possible strategies
enabling cross-coupling using arenes as pro-nucleophiles, reductive
dehydrocoupling, or deuteration of B–H bonds are discussed.