Mechanism-Driven Optimization of Proton Transfer in Mn-Catalyzed Amine-Boranes Dehydrogenation: The Way to Turbo Mode
- 1A. N. Nesmeyanov Institute of Organoelement Compounds (INEOS, Russian Academy of Sciences, 28/1 Vavilov str., GSP-1, Moscow, Russian Federation, 119334
- 2Univ Toulouse, 205 route de Narbonne, Toulouse Cedex, France, 31077
Abstract
Improving the efficiency of the individual steps in catalytic cycles is one of the main cornerstones of homogeneous catalysis. In particular, optimization of proton transfer processes by the incorporation of nitrogen donor moieties in the second coordination sphere of transition metal constitutes a privileged strategy to boost the rate and modulate the selectivity of electrocatalysts for small molecules activation. However, proton-relay strategies remain largely unexplored in homogeneous (de)hydrogenation, particularly through the use of exogenous nitrogen bases. We report herein that the rational choice of amine additive as proton transfer mediator can largely improve efficient Mn-based catalytic system for amine-borane dehydrogenation working through the cooperation between Mn+ and MnH species. Addition of 1.0-5.0 mol% of simple tertiary amine such as Et3N led to 7-45-fold rate acceleration and the increase of TON values by 65-420% for all substrates. This upgrade is due to a combination of lower activation barrier for the rate-determining deprotonation of Mn-coordinated amine-boranes and a higher amount of catalytically active cationic metal species Mn+ present in solution under these conditions. In addition, meticulous mechanistic investigations revealed the crucial role of ammonium salt concentration in this catalytic process thus paving the way for further improvements. Accordingly, the use of a binary Et3N/Et3NH+ mixture instead of pure Et3N again speeds up Mn-catalyzed Me2NHBH3 dehydrogenation by a factor of ten to achieve unprecedented TOF of 125 s−1 and TON of 105 at 60°C. Beyond achieving the best performance reported to date for this substrate, our results highlight how the judicious optimization of a priori trivial elementary steps in the catalytic cycle, without altering the intrinsic reactivity of the metal center, can dramatically enhance the activity of an already highly efficient transition metal catalyst.
Related
- Optimization of the intramolecular cyclization to form the clozapine lactam intermediate under continuous-flow conditions and elucidation of the H2SO4-catalyzed mechanism by DFT
- Topology Optimization and Dynamic Heat Transfer Mechanism of Liquid Cold Plates for Lithium-Ion Battery Thermal Management
- Rhodium‐Catalyzed Synthesis of Enantioenriched α‐Substituted Primary Amines Through Asymmetric Transfer Hydrogenation
- Synthesis of Dihydro-indolo-oxazines via a RedOx‑Neutral, Gold‑Catalyzed Hydride‑Transfer Process
- Ru‐Catalyzed Asymmetric Transfer Hydrogenation of α‐iminophosphonates: A Novel Synthetic Approach for Valuable Chiral α‐Aminophosphonates
BibTeX
@misc{gulyaeva2026mechanismdriven,
title = {{Mechanism-Driven Optimization of Proton Transfer in Mn-Catalyzed Amine-Boranes Dehydrogenation: The Way to Turbo Mode}},
author = {Ekaterina S. Gulyaeva and Mikhail D. Rodkin and Sergey A. Kovalenko and Elena S. Osipova and Oleg A. Filippov and Natalia V. Belkova and Yves Canac and Elena S. Shubina and Dmitry A. Valyaev},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15011066/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15011066/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Mechanism-Driven Optimization of Proton Transfer in Mn-Catalyzed Amine-Boranes Dehydrogenation: The Way to Turbo Mode
AU - Ekaterina S. Gulyaeva
AU - Mikhail D. Rodkin
AU - Sergey A. Kovalenko
AU - Elena S. Osipova
AU - Oleg A. Filippov
AU - Natalia V. Belkova
AU - Yves Canac
AU - Elena S. Shubina
AU - Dmitry A. Valyaev
PY - 2026
DA - 2026/10/26
PB - ChemRxiv
DO - 10.26434/chemrxiv.15011066/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15011066/v1
AB - Improving the efficiency of the individual steps in catalytic cycles is one of the main cornerstones of homogeneous catalysis. In particular, optimization of proton transfer processes by the incorporation of nitrogen donor moieties in the second coordination sphere of transition metal constitutes a privileged strategy to boost the rate and modulate the selectivity of electrocatalysts for small molecules activation. However, proton-relay strategies remain largely unexplored in homogeneous (de)hydrogenation, particularly through the use of exogenous nitrogen bases. We report herein that the rational choice of amine additive as proton transfer mediator can largely improve efficient Mn-based catalytic system for amine-borane dehydrogenation working through the cooperation between Mn+ and MnH species. Addition of 1.0-5.0 mol% of simple tertiary amine such as Et3N led to 7-45-fold rate acceleration and the increase of TON values by 65-420% for all substrates. This upgrade is due to a combination of lower activation barrier for the rate-determining deprotonation of Mn-coordinated amine-boranes and a higher amount of catalytically active cationic metal species Mn+ present in solution under these conditions. In addition, meticulous mechanistic investigations revealed the crucial role of ammonium salt concentration in this catalytic process thus paving the way for further improvements. Accordingly, the use of a binary Et3N/Et3NH+ mixture instead of pure Et3N again speeds up Mn-catalyzed Me2NHBH3 dehydrogenation by a factor of ten to achieve unprecedented TOF of 125 s−1 and TON of 105 at 60°C. Beyond achieving the best performance reported to date for this substrate, our results highlight how the judicious optimization of a priori trivial elementary steps in the catalytic cycle, without altering the intrinsic reactivity of the metal center, can dramatically enhance the activity of an already highly efficient transition metal catalyst.
ER -