Rivier, Lucie; Peljo, Pekka; Maye, Sunny; Méndez, Manuel A.; Vrubel, Heron; Vannay, Laurent A.C.; Corminboeuf, Clémence; Scanlon, Micheál D. and Girault, Hubert H.

2019

July

Chemistry A European Journal

Mechanistic study of the photo-generation of hydrogen by decamethylruthenocene

Published

5 ()

25

55

12769

12779

Hydrogen evolution by decamethylruthenocene (Cp*2RuII) was studied in detail highlighting that metallocenes are capable of photo-reducing hydrogen without the need of an additional sensitizer. Electrochemical, gas chromatographic and spectroscopic (UV/vis, 1H and 13C NMR) measurements corroborated by density functional theory (DFT) calculations indicate that the production of hydrogen occurs by a two-step process. First, the decamethylruthenocene hydride ([Cp*2RuIV(H)]+) is formed in the presence of an organic acid. Subsequently, [Cp*2RuIV(H)]+ is reversibly reduced via a heterolytic reaction with one-photon excitation leading to a first release of hydrogen. Thereafter, the resultant decamethylruthenocenium ion ([Cp*2RuIII]+) is further reduced leading to a second release of hydrogen by deprotonation of a methyl group of [Cp*2RuIII]+. Experimental and computational data show the spontaneous conversion of [Cp*2RuII] to [Cp*2RuIV(H)]+ in the presence of protons. Calculations highlight that the first reduction is endergonic (G0 = 108 kJ·mol−1) and needs an input of energy by light for the reaction to occur. The hydricity of the methyl protons of [Cp*2RuII] was also considered.

https://onlinelibrary.wiley.com/doi/abs/10.1002/chem.201902353

10.1002/chem.201902353