Photophysics and Photochemistry of 2,2'-Bipyridine and 1,10-Phenanthroline Complexes of Vanadium(II)
The lifetimes of the lowest energy excited states of V(bpy)32+ (bpy = 2,2/-bipyridine) and V(phen)32+ (phen = 1,10-phenanthroline) are 500 ps and 1.8 ns, respectively, in ethanol at room temperature. These lifetimes are much shorter than those for the isoelectronic chromium(III) complexes. The lowest energy excited states in the vanadium systems are probably either 2E/2T1 or quartet MLCT states. Electrode potentials for the V(NN)33+/2+ couples are approximately 0.09 (NN = bpy) and 0.13 V (NN = phen) in CH3CN vs. Fc/Fc+ (Fc = ferrocene), based on cyclic voltammetry data. Irradiation of V(phen)32+ in its lowest energy electronic absorption band λmax=640 nm) in the presence of various electron acceptors results in one-electron oxidation and ultimate formation of (phen)2V(μ-OH)2V(phen)24+. Similar photoredox processes are observed for V(bpy)32+. The photooxidation mechanism involves oxidative quenching of the V(NN)32+ excited state, followed by hydrolysis and dimerization of V(NN)33+. © 1986, American Chemical Society. All rights reserved.
Publication Source (Journal or Book title)
Shah, S., & Maverick, A. (1986). Photophysics and Photochemistry of 2,2'-Bipyridine and 1,10-Phenanthroline Complexes of Vanadium(II). Inorganic Chemistry, 25 (11), 1867-1871. https://doi.org/10.1021/ic00231a031