Mechanisms of Reaction of Organometallic Complexes

Abstract

An overview of the mechanistic features of organometallic reactions is presented. The primary mechanistic types discussed are ligand substitution, oxidative addition, reductive elimination, and electron transfer. Each reaction pathway is discussed within the context of the common electron counts encountered for most organometallic complexes. Examples of how these common reaction pathways extend to polynuclear complexes are also presented. Although reasonable generalizations with regard to overall reaction rates and stepwise mechanisms using the electron count formalism can be made, many recent reports point out that the details of ligand and metal center structure can override these general trends. A considerable amount of quantitative rate data is provided and computational methodologies for understanding the observed rates are discussed.

Mechanism of Rhodium-Catalyzed Intramolecular Hydroacylation: A Computational Study

“…Interestingly, both of the isomers with the acyl group apical are lower in energy than those that possess the hydride apical. This is counter to the typical order known for the trans influence of ligands and has significant implications for the catalytic pathway, which will be discussed below.…”

Mononuclear Organometallic Pd(II), Pd(III), and Pd(IV) Complexes Stabilized by a Pyridinophane Ligand with a C-Donor Group

“…X-ray crystallography of 3 reveals that the Pd III center adopts a distorted octahedral geometry, with one chloride anion and one MeCN ligand bound equatorially to the Pd center (Scheme and Figure ). The chloride ligand is bound trans to the pyridyl N atom, while the more weakly interacting MeCN ligand is bound trans to the phenyl C atom, as expected due the significant trans influence of the phenyl group. , Importantly, since in 3 the C ipso –H bond has been activated upon oxidation and a Pd III –C bond has been formed, we propose that C–H bond activation has been promoted by the oxidation of 2b and thus has likely occurred at a Pd III (or Pd IV ) center, in a similar manner to what we observed recently for analogous Ni complexes. − …”

An Easy Conversion from Platinum(II) Reagents to Platinum(IV) Products: κ3 to κ2 Coordination Mode Interconversion, Phenyl Migration, and Ortho C–H Activation Cascade in a Hemilabile “Click”-Triazole Scorpionate Platinum System

“…An Eyring plot (Figure ) was constructed using rate constants from a temperature range of 245–270 K: Δ H ⧧ and Δ S ⧧ are 25.5(±0.7) kcal/mol and +23(±3) eu, respectively. The large positive value for Δ S ⧧ suggests that the rate-determining step is the reductive elimination of benzene to form two species . Note that the putative η 2 -benzene intermediate was never observed.…”