Abstract
Two isomers, [Ru(1)] 2+ (Ru = Ru(bpy) 2, bpy = 2,2′-bipyridine, 1 = 2-(pyrid-2′-yl)-1-azaacridine) and [Ru(2)] 2+ (2 = 3-(pyrid-2′-yl)-4-azaacridine), are bio-inspired model compounds containing the nicotinamide functionality and can serve as precursors for the photogeneration of C-H hydrides for studying reactions pertinent to the photochemical reduction of metal-C 1 complexes and/or carbon dioxide. While it has been shown that the structural differences between the azaacridine ligands of [Ru(1)] 2+ and [Ru(2)] 2+ have a significant effect on the mechanism of formation of the hydride donors, [Ru(1HH)] 2+ and [Ru(2HH)] 2+, in aqueous solution, we describe the steric implications for proton, net-hydrogen-atom and net-hydride transfer reactions in this work. Protonation of [Ru(2 •-)] + in aprotic and even protic media is slow compared to that of [Ru(1 •-)] +. The net hydrogen-atom transfer between *[Ru(1)] 2+ and hydroquinone (H 2Q) proceeds by one-step EPT, rather than stepwise electron-proton transfer. Such a reaction was not observed for *[Ru(2)] 2+ because the non-coordinated N atom is not easily available for an interaction with H 2Q. Finally, the rate of the net hydride ion transfer from [Ru(1HH)] 2+ to [Ph 3C] + is significantly slower than that of [Ru(2HH)] 2+ owing to steric congestion at the donor site.
| Original language | English |
|---|---|
| Pages (from-to) | 129-144 |
| Number of pages | 16 |
| Journal | Faraday Discussions |
| Volume | 155 |
| DOIs | |
| Publication status | Published - 2012 |
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ASJC Scopus subject areas
- Physical and Theoretical Chemistry
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Steric effect for proton, hydrogen-atom, and hydride transfer reactions with geometric isomers of NADH-model ruthenium complexes. / Cohen, Brian W.; Polyansky, Dmitry; Achord, Patrick; Cabelli, Diane; Muckerman, James; Tanaka, Koji; Thummel, Randolph P.; Zong, Ruifa; Fujita, Etsuko.
In: Faraday Discussions, Vol. 155, 2012, p. 129-144.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Steric effect for proton, hydrogen-atom, and hydride transfer reactions with geometric isomers of NADH-model ruthenium complexes
AU - Cohen, Brian W.
AU - Polyansky, Dmitry
AU - Achord, Patrick
AU - Cabelli, Diane
AU - Muckerman, James
AU - Tanaka, Koji
AU - Thummel, Randolph P.
AU - Zong, Ruifa
AU - Fujita, Etsuko
PY - 2012
Y1 - 2012
N2 - Two isomers, [Ru(1)] 2+ (Ru = Ru(bpy) 2, bpy = 2,2′-bipyridine, 1 = 2-(pyrid-2′-yl)-1-azaacridine) and [Ru(2)] 2+ (2 = 3-(pyrid-2′-yl)-4-azaacridine), are bio-inspired model compounds containing the nicotinamide functionality and can serve as precursors for the photogeneration of C-H hydrides for studying reactions pertinent to the photochemical reduction of metal-C 1 complexes and/or carbon dioxide. While it has been shown that the structural differences between the azaacridine ligands of [Ru(1)] 2+ and [Ru(2)] 2+ have a significant effect on the mechanism of formation of the hydride donors, [Ru(1HH)] 2+ and [Ru(2HH)] 2+, in aqueous solution, we describe the steric implications for proton, net-hydrogen-atom and net-hydride transfer reactions in this work. Protonation of [Ru(2 •-)] + in aprotic and even protic media is slow compared to that of [Ru(1 •-)] +. The net hydrogen-atom transfer between *[Ru(1)] 2+ and hydroquinone (H 2Q) proceeds by one-step EPT, rather than stepwise electron-proton transfer. Such a reaction was not observed for *[Ru(2)] 2+ because the non-coordinated N atom is not easily available for an interaction with H 2Q. Finally, the rate of the net hydride ion transfer from [Ru(1HH)] 2+ to [Ph 3C] + is significantly slower than that of [Ru(2HH)] 2+ owing to steric congestion at the donor site.
AB - Two isomers, [Ru(1)] 2+ (Ru = Ru(bpy) 2, bpy = 2,2′-bipyridine, 1 = 2-(pyrid-2′-yl)-1-azaacridine) and [Ru(2)] 2+ (2 = 3-(pyrid-2′-yl)-4-azaacridine), are bio-inspired model compounds containing the nicotinamide functionality and can serve as precursors for the photogeneration of C-H hydrides for studying reactions pertinent to the photochemical reduction of metal-C 1 complexes and/or carbon dioxide. While it has been shown that the structural differences between the azaacridine ligands of [Ru(1)] 2+ and [Ru(2)] 2+ have a significant effect on the mechanism of formation of the hydride donors, [Ru(1HH)] 2+ and [Ru(2HH)] 2+, in aqueous solution, we describe the steric implications for proton, net-hydrogen-atom and net-hydride transfer reactions in this work. Protonation of [Ru(2 •-)] + in aprotic and even protic media is slow compared to that of [Ru(1 •-)] +. The net hydrogen-atom transfer between *[Ru(1)] 2+ and hydroquinone (H 2Q) proceeds by one-step EPT, rather than stepwise electron-proton transfer. Such a reaction was not observed for *[Ru(2)] 2+ because the non-coordinated N atom is not easily available for an interaction with H 2Q. Finally, the rate of the net hydride ion transfer from [Ru(1HH)] 2+ to [Ph 3C] + is significantly slower than that of [Ru(2HH)] 2+ owing to steric congestion at the donor site.
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U2 - 10.1039/c1fd00094b
DO - 10.1039/c1fd00094b
M3 - Article
VL - 155
SP - 129
EP - 144
JO - Faraday Discussions
JF - Faraday Discussions
SN - 1364-5498
ER -