Rebound or cage escape?: the role of the rebound barrier for the reactivity of non-heme high-valent FeIV=O species
Owing to their high reactivity and selectivity, variations in the spin ground state and a range of possible pathways, high-valent FeIV=O species are popular models with potential bioinspired applications. An interesting example of a structure-reactivity pattern is the detailed study with five nonhem...
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| Main Authors: | , , , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
06 November 2023
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| In: |
Chemistry - a European journal
Year: 2023, Pages: 1-11 |
| ISSN: | 1521-3765 |
| DOI: | 10.1002/chem.202303300 |
| Online Access: | Verlag, kostenfrei, Volltext: https://doi.org/10.1002/chem.202303300 Verlag, kostenfrei, Volltext: https://onlinelibrary.wiley.com/doi/abs/10.1002/chem.202303300 
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| Author Notes: | Ravi Kumar, Azaj Ansari, Peter Comba, Gopalan Rajaraman |
| Summary: | Owing to their high reactivity and selectivity, variations in the spin ground state and a range of possible pathways, high-valent FeIV=O species are popular models with potential bioinspired applications. An interesting example of a structure-reactivity pattern is the detailed study with five nonheme amine-pyridine pentadentate ligand FeIV=O species, including N4py: [(L1)FeIV=O]2+ (1), bntpen: [(L2)FeIV=O]2+ (2), py2tacn: [(L3)FeIV=O]2+ (3), and two isomeric bispidine derivatives: [(L4)FeIV=O]2+ (4) and [(L5)FeIV=O]2+ (5). In this set, the order of increasing reactivity in the hydroxylation of cyclohexane differs from that with cyclohexadiene as substrate. A comprehensive DFT, ab initio CASSCF/NEVPT2 and DLPNO-CCSD(T) study is presented to untangle the observed patterns. These are well reproduced when both activation barriers for the C−H abstraction and the OH rebound are taken into account. An MO, NBO and deformation energy analysis reveals the importance of π(pyr) → π*xz(FeIII-OH) electron donation for weakening the FeIII-OH bond and thus reducing the rebound barrier. This requires that pyridine rings are oriented perpendicularly to the FeIII-OH bond and this is a subtle but crucial point in ligand design for non-heme iron alkane hydroxylation. |
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| Item Description: | Im Zusatz zum Titel ist "VI" hochgestellt Gesehen am 25.01.2024 |
| Physical Description: | Online Resource |
| ISSN: | 1521-3765 |
| DOI: | 10.1002/chem.202303300 |