Volume 155, 2012

Steric effect for proton, hydrogen-atom, and hydride transfer reactions with geometric isomers of NADH–model ruthenium complexes

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–C1 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 (H2Q) 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 H2Q. Finally, the rate of the net hydride ion transfer from [Ru(1HH)]2+ to [Ph3C]+ is significantly slower than that of [Ru(2HH)]2+ owing to steric congestion at the donor site.

Supplementary files

Article information

Article type
Paper
Submitted
18 May 2011
Accepted
23 May 2011
First published
06 Jul 2011

Faraday Discuss., 2012,155, 129-144

Steric effect for proton, hydrogen-atom, and hydride transfer reactions with geometric isomers of NADH–model ruthenium complexes

B. W. Cohen, D. E. Polyansky, P. Achord, D. Cabelli, J. T. Muckerman, K. Tanaka, R. P. Thummel, R. Zong and E. Fujita, Faraday Discuss., 2012, 155, 129 DOI: 10.1039/C1FD00094B

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements