期刊
INORGANIC CHEMISTRY
卷 49, 期 17, 页码 8034-8044出版社
AMER CHEMICAL SOC
DOI: 10.1021/ic101098v
关键词
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资金
- University of Houston [DE-FG03-02ER15334]
- BNL [DE-AC02-98CH10886]
- U.S. Department of Energy
- Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences
- U.S. Department of Energy for funding under the BES Solar Energy Utilization Initiative
The pH-dependent mechanism of the reduction of the nicotinamide adenine dinucleotide (NADH) model complex [Ru(bpy)(2)(5)](2+) (5 = 3-(pyrid-2'-yl)-4-azaacridine) was compared to the mechanism of the previously studied geometric isomer [Ru(bpy)(2)(pbn)](2+) (pbn = 2-(pyrid-2'-yl)-1-azaacridine, previously referred to as 2-(pyrid-2'-yl)benzo[b]-1,5-naphthyridine) in aqueous media. The exposure of [Ru(bpy)(2)(5)](2+) to CO2 center dot- leads to the formation of the one-electron reduced species (k = 4.4 x 10(9) M-1 s(-1)). At pH < 11.2, the one-electron reduced species can be protonated, k= 2.6 x 10(4) s(-1) in D2O. Formation of a C-C bonded dimer is observed across the pH range of 5-13 (k = 4.5 X 10(8) M-1 S-1). At pH < 11, two protonated radical species react to form a stable C-C bonded dimer. At pH > 11, dimerization of two one-electron reduced species is followed by disproportionation to one equivalent starting complex [Ru(bpy)(2)(5)](2+) and one equivalent [Ru(bpy)(2)(5HH)](2+). The structural difference between [Ru(bpy)(2)(pbn)](2+) and [Ru(bpy)(2)(5)](2+) dictates the mechanism and product formation in aqueous medium. The exchange of the nitrogen and carbon atoms on the azaacridine ligands alters the accessibility of the dimerization reactive site, thereby changing the mechanism and the product formation for the reduction of the [Ru(bpy)(2)(5)](2+) compound.
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