Oxidative Addition: C-–H Bond Activation by Fe(CO)4

Usage

The adf.rkf file for this example can be downloaded here:

1. Download Oxidative_Addition.adf.rkf

2. Open the PyOrbb application.

3. Drag the .adf.rkf file to the GUI.

Now the most important interactions will appear. To further study fragment orbitals that interact, the user will want to visualize the orbitals:

4. Select the orbital of interest.

5. Click on the orbital (\(\varphi\)).

Now the PyOrbb viewer window will open with many options for drawing the orbitals.

Once the previous steps have been completed, the user should be able to reproduce the following analysis [1] [2].

Analysis

Catalytic reactions are indispensable tools in modern synthetic chemistry. The oxidative addition step is often the first and rate-determining step in transition metal catalysis. In this example, we analyze the transition state of the oxidative addition of an iron complex into the methane C–H bond. PyOrbb correctly identified the key orbital interaction mechanism (See below).

We see two major orbital interaction patterns, namely, the interaction between CH₄(5A) and Fe(CO)₄(42A), which corresponds to the \(\sigma\)-donation from the C–H orbital of CH₄ to the d orbital of Fe(CO)₄. PyOrbb also finds the \(\pi\)-backdonation interaction between CH₄(6A) and Fe(CO)₄(41A), which involves donation of electrons from the d orbital of Fe(CO)₄ to the \(\sigma^{*}\)-C–H orbital of CH₄.

References

[1]

X. Sun, M. V. J. Rocha, T. A. Hamlin, J. Poater, and F. M. Bickelhaupt, “Understanding the differences between iron and palladium in cross-coupling reactions,” Physical Chemistry Chemical Physics 21 (2019): 9651–9664, https://doi.org/10.1039/c8cp07671e.

[2]

Yuman Hordijk, Steven E. Beutick, Xiaobo Sun, Laurens Groot, Tori Gijzen, Jordi Poater, Trevor A. Hamlin, F. Matthias Bickelhaupt, Célia Fonseca Guerra, “PyOrbb – Automated Analyses of Orbital-Interaction Mechanisms” Journal of Computational Chemistry, 2026, e70512, DOI=https://doi.org/10.1002/jcc.70512.