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Updated: Jun 19, 2026

Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene
Published on: March 20, 2017
Oxidation of cyclohexane by high-valent iron bispidine complexes: tetradentate versus pentadentate ligands
Peter Comba1, Martin Maurer, Prabha Vadivelu
1Universität Heidelberg, Anorganisch-Chemisches Institut, INF 270, D-69120 Heidelberg, Germany. peter.comba@aci.uni-heidelberg.de
Abstract:
The iron-bispidine-catalyzed oxidation of cyclohexane with H(2)O(2), where either a tetradentate or a pentadentate bispidine ligand is coordinated to the iron center, yields up to 35% cyclohexanol and cyclohexanone (alcohol/ketone ratio of up to 4). Product distribution (including (18)O labeling studies), kinetic isotope effects, and the ratio of tertiary/secondary alcohols with adamantane as a substrate (tertiary/secondary) suggest that (i) H abstraction by a ferryl complex is the rate-determining step and that the emerging cyclohexyl radical is short-lived, (ii) there is a parallel reaction involving oxidation by OH radicals, and (iii) there are considerable differences in the reaction pathways between the tetradentate and pentadentate ligand catalyst. These interpretations are fully supported by a DFT-based computational analysis.
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