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A Frustrated Phosphane-Borane Lewis Pair and Hydrogen: A Kinetics Study.
Thomas Özgün1, Klaus Bergander1, Lei Liu2
1Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, 48149, Münster, Corrensstrasse 40, Germany.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|June 30, 2016
Summary
Frustrated Lewis pairs (FLPs) enable endothermic H2 cleavage. This study quantines the kinetics of H2 elimination in a phosphane-borane FLP system, providing key insights into FLP reactivity.
Area of Science:
- Organometallic Chemistry
- Chemical Kinetics
- Computational Chemistry
Background:
- Frustrated Lewis pairs (FLPs) are reactive species that can activate small molecules.
- Understanding the energy profiles and kinetics of FLP reactions is crucial for catalyst design.
Purpose of the Study:
- To determine the energy profile of a frustrated Lewis pair (FLP) dihydrogen splitting system.
- To investigate the kinetics and mechanism of H2 cleavage by a phosphane-borane FLP.
Main Methods:
- Combined experimental kinetic studies and Density Functional Theory (DFT) calculations.
- Measurement of rate constants for H2 elimination.
- Determination of primary kinetic isotope effects (KIEs).
Main Results:
- A trimethylene-bridged phosphane-borane FLP was converted into its endothermic H2 cleavage product.
- The rate constant for H2 elimination at 299 K was determined to be (2.87±0.1)×10⁻⁴ s⁻¹.
- A primary kinetic isotope effect (kHH/kDD)exp of 3.19 was observed.
- DFT calculations accurately reproduced the experimental findings.
Conclusions:
- The study provides a detailed kinetic and energetic analysis of H2 splitting by a phosphane-borane FLP.
- The results offer valuable data for understanding FLP reactivity and designing new catalytic systems for H2 activation.
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