Synthesis and Application of Planar Chiral NHC/Rh Complexes Bearing CoC4Ph4 Group

Sandwich compound-based planar chiral N-heterocyclic carbene (NHC) ligands having a bulky η5-cyclopentadienyl-cobalt-η4-tetraphenylcyclobutadiene core were developed, and their donor strengths were evaluated by determining the Tolman electronic parameter (TEP) of the Rh dicarbonyl complex. The TEP was high at 2048 cm-1, as expected for an NHC ligand. The utility of the carbenes as chiral ligands was examined in the Rh-catalyzed asymmetric ring-opening reaction of oxabenzonorbornadienes with benzylamine, and the corresponding products were obtained with moderate enantioselectivities (up to 66% ee).

A crystalline cyclic (alkyl)(amino)carbene with a 1,1'-ferrocenylene backbone

Cyclic (alkyl)(amino)carbenes with a 1,1'-ferrocenylene backbone (fcCAACs) are established as an original family by the preparation of a crystalline congener. The C_carbene bond angle is unprecedentedly wide for a CAAC, causing an exceptionally pronounced ambiphilicity. The redox-active backbone opens the door to unconventional metalloradicals and oligoradicals.

Forever young: the first seventy years of ferrocene

The discovery of ferrocene, [Fe(η5-C5H5)2], seventy years ago has significantly influenced chemical research and provided a key impetus for establishing and rapidly expanding organometallic chemistry, which has continued at a...

Pyrrolinium-Substituted Persistent Zwitterionic Ferrocenate Derivative Enabling the Application of Ferrocene Anolyte

Here, we report the imidazolium-/pyrrolinium-substituted persistent zwitterionic ferrocenate derivatives, which were characterized by electron paramagnetic resonance (EPR) and ⁵⁷Fe Mössbauer spectroscopy. Additional theoretical studies on these zwitterionic ferrocenate derivatives clearly explain the origin of their thermal stability and the orbital interactions between iron and imidazolium-/pyrrolinium-substituted zwitterionic cyclopentadienyl ligand. Exploiting the facile Fe(II/I) redox chemistry, we successfully demonstrated that the pyrrolinium-substituted ferrocene derivative can be applied as an example of derivatized ferrocene anolyte for redox-flow batteries. These zwitterionic ferrocenate derivatives will not only deepen our understanding of the intrinsic chemistry of ferrocenate but have the potential to open the way for the rational design of metallocenate derivatives for various applications.