Reversible α-Hydrogen and α-Alkyl Elimination in PC(sp(3))P Pincer Complexes of Iridium

Angew Chem Int Ed Engl. 2015 Aug 3;54(32):9372-5. doi: 10.1002/anie.201503593. Epub 2015 Jun 26.

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.

Keywords: density functional calculations; elimination; iridium; kinetics; pincer complexes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Coordination Complexes / chemical synthesis
  • Coordination Complexes / chemistry*
  • Crystallography, X-Ray
  • Hydrogen / chemistry*
  • Iridium / chemistry*
  • Molecular Conformation
  • Quantum Theory
  • Thermodynamics

Substances

  • Coordination Complexes
  • Iridium
  • Hydrogen