Ir-PCP-pincer C-H activation catalysts

The activation of C-H bonds is often attempted with transition metal complex catalysts. A particular type of such complexes, which catalyze direct rather than transfer dehydrogenation, bears a P-C-P pincer ligand (see formula).

Theoretical calculations suggest that the oxidation state of the central metal atom (e.g., Ir) plays an important role.
We investigate examples of Ir P-C-P complexes by electrochemical techniques in combination with computer simulations. The CH₃O-substituted molecule is known to undergo an intra-molecular activation of a C-H bond in the tert-butyl substituent. The overall reaction mechanism is described by a "square scheme".

In the case of the unsubstituted parent compound this scheme is extended by further electron transfer and chemical steps.

Coworkers in this project

Filip Novak and Gloria M. Quintanilla

We closely cooperate with the group of

Hermann A. Mayer.

We acknowledge funding of this project by the Deutsche Forschungsgemeinschaft, Bonn - Bad Godesberg (within the Graduiertenkolleg "Chemie in Interphasen") and the Max-Buchner-Forschungsstiftung.

Publications from this project

H.A.Y. Mohammad, J.C. Grimm, K. Eichele, H.-G. Mack, B. Speiser, F. Novak, W.C. Kaska und H. A. Mayer, Double Cyclometalation: Implications for C-H Oxidative Addition With PCP Pincer Compounds of Iridium, in K.I. Goldberg und A.S. Goldman (Eds.), "Activation and Functionalization of C-H Bonds", ACS Symposium Series, American Chemical Society, No. 885, Kapitel 14, S. 234 - 247 (2004).

F. Novak, B. Speiser, H.A.Y. Mohammad und H.A. Mayer, Electrochim. Acta, 49, 3841 - 3853 (2004); Electrochemistry of Transition Metal Complex Catalysts. Part 10. Intra- and Intermolecular Electrochemically Activated C-H Addition to the Central Metal Atom of a P-C-P-Pincer Iridium Complex.

H.A.Y. Mohammad, J.C. Grimm, K. Eichele, H.-G. Mack, B. Speiser, F. Novak, M.G. Quintanilla, W.C. Kaska und H.A. Mayer, Organometallics 21, 5775 - 5784 (2002); C-H Oxidative Addition with a (PCP)Ir^III-Pincer-Complex.