Insights into the use of [Ru(p-Cym)(bipy)Cl]Cl as precatalyst for solvolytic dehydrogenation of ammonia-borane

•New [Ru(p-Cym)(bipy)(NH3)](PF6)2 and [Ru(p-Cym)(bipy)Cl](BArF4) were synthesized.•A method for the activation of Ru(II)-Cl for the dehydrogenation of AB was developed.•[Ru(p-Cym)(bipy)(NH3)]2+ was identified as the dormant state of the catalyst.•In situ formed [Ru(p-Cym)(bipy)H]+ was fully characterized spectroscopically.

A detailed study on the use of [Ru(p-Cym)(bipy)Cl]Cl as precatalyst for the solvolytic dehydrogenation of ammonia-borane (AB) is presented. A new [Ru(p-Cym)(bipy)(NH3)](PF6) was synthesized and its dication identified as the dormant state of the catalyst after release of the hydrogen pressure from the reaction mixture. Exhaustive analysis of the activation procedure permitted us to establish an optimized experimental protocol to form the actual catalyst from either [Ru(p-Cym)(bipy)Cl]Cl or related precursors. Following this procedure, 2.62 equivalents of hydrogen per mol of ammonia-borane were released in 2.7 min at 49 °C. Kinetic experiments and a comparison on the use of different precatalysts are also presented.

Graphical abstractA detailed study on the use of [Ru(p-Cym)(bipy)Cl]Cl as precatalyst for the solvolytic dehydrogenation of ammonia-borane (AB) is presented. With this catalytic system up to 2.62 equivalents of hydrogen per mol of ammonia-borane were released in 2.7 min at 49 °C. Kinetic experiments and a comparison on the use of related precatalysts are also discussed.Figure optionsDownload full-size imageDownload as PowerPoint slide