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A Simple, Low-cost, and Robust System to Measure the Volume of Hydrogen Evolved by Chemical Reactions with Aqueous Solutions
Published on: August 17, 2016
Experimental Evaluation of the Hydricity of Hydrosilanes
Laurent Sévery1, Emmanuel Nicolas1, Alexis Mifleur1
1NIMBE, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France.
Abstract:
Despite their widespread use as reductants, the thermodynamic hydricities of hydrosilanes have not been determined experimentally. We report the hydricities of three triarylsilanes determined by a combination of hydride-exchange reactions and electrochemical measurements of the corresponding silylium cations. The hydricities in acetonitrile for Xyl3SiH (89.0 kcal·mol-1, Xyl = 2,6-dimethylphenyl), Mes3SiH (86.6 kcal·mol-1, Mes = 2,4,6-trimethylphenyl), and PEMP3SiH (80.5 kcal·mol-1, PEMP = pentamethylphenyl) were estimated from the one-electron reduction potentials of the silylium ions in 1,2-difluorobenzene and are higher than previously reported values obtained by calculations. The reaction of [PEMP3Si][B(C6F5)4] with cycloheptatriene (CHT) in 1,2-difluorobenzene/C6D6 (4:1) attained an equilibrium (K ≈ 1.3), indicating similar hydricities for CHT and PEMP3SiH.
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