Reversible α‐Hydrogen and α‐Alkyl Elimination in PC(sp³)P Pincer Complexes of Iridium

Abstract

Despite significant progress in recent years, the cleavage of unstrained C(sp(3))-C(sp(3)) bonds remains challenging. A C-C coupling and cleavage reaction in a PC(sp(3))P iridium pincer complex is mechanistically studied; the reaction proceeds via the formation of a carbene intermediate and can be described as a competition between α-hydrogen and α-alkyl elimination; the latter process was observed experimentally and is an unusual way of C(sp(3))-C(sp(3)) bond scission, which has previously not been studied in detail. Mechanistic details that are based upon kinetic studies, activation parameters, and DFT calculations are also discussed. A full characterization of a C-C agostic intermediate is presented.

Facile generation of iridium PCcarbeneP pincer complexes via water elimination from an alcohol proligand

“…8a α-Alkyl elimination in closely related iridium PCP complexes has been directly observed by Wendt. 20 The product of C-O activation, inter- Intermediate VI can in-principle also be generated from β-hydride elimination from an α-hydroxylalkyl ligand (i.e. from III of pathway A, Scheme 4).…”

Reversible Carbon–Carbon Bond Breaking and Spin Equilibria in Bis(pyrimidinenorcorrole)

“…In some instances, the bonded and dissociated state are so close in energy that dynamic bond breaking occurs rapidly under ambient conditions; otherwise, an external stimulus (thermal or photochemical) is required to drive the process . Intramolecular dissociation can be particularly facile, leading to various rearrangement reactions ,,,,,–. However, the most intriguing processes are those occurring in an intermolecular fashion as they provide access to unique dynamic structures, such as self‐healing polymers .…”

Transition‐Metal Complexes with (C–C)→M Agostic Interactions

“…Very recently another apparent (C–C) agostic complex was isolated by the pincer strategy . The complex was prepared by oxidative addition of CH 3 I to an Ir I complex, during which a N 2 ligand was displaced.…”