A New Homogeneous Catalyst for the Dehydrogenation of Dimethylamine Borane Starting with Ruthenium(III) Acetylacetonate

Materials

Ebru Ünel Barın²  Mehdi Masjedi²  Saim Özkar¹ 

[1] Department of Chemistry, Middle East Technical University, 06800 Ankara, Turkey;

关键词: ruthenium;    acetylacetonate;    hydrogen generation;    dimethylamine borane;    dehydrogenation;    homogeneous catalysis;   

DOI  :  10.3390/ma8063155

来源: mdpi

【 摘 要 】

The catalytic activity of ruthenium(III) acetylacetonate was investigated for the first time in the dehydrogenation of dimethylamine borane. During catalytic reaction, a new ruthenium(II) species is formed in situ from the reduction of ruthenium(III) and characterized using UV-Visible, Fourier transform infrared (FTIR), ¹H NMR, and mass spectroscopy. The most likely structure suggested for the ruthenium(II) species is mer-[Ru(N₂Me₄)₃(acac)H]. Mercury poisoning experiment indicates that the catalytic dehydrogenation of dimethylamine-borane is homogeneous catalysis. The kinetics of the catalytic dehydrogenation of dimethylamine borane starting with Ru(acac)₃ were studied depending on the catalyst concentration, substrate concentration and temperature. The hydrogen generation was found to be first-order with respect to catalyst concentration and zero-order regarding the substrate concentration. Evaluation of the kinetic data provides the activation parameters for the dehydrogenation reaction: the activation energy E_a = 85 ± 2 kJ·mol⁻¹, the enthalpy of activation ∆H^# = 82 ± 2 kJ·mol⁻¹ and the entropy of activation; ∆S^# = −85 ± 5 J·mol⁻¹·K⁻¹. The ruthenium(II) catalyst formed from the reduction of ruthenium(III) acetylacetonate provides 1700 turnovers over 100 hours in hydrogen generation from the dehydrogenation of dimethylamine borane before deactivation at 60 °C.

【 授权许可】

CC BY   
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