On the electrochemical reduction of some Cr(III) complexes inDMSO investigated by cyclic voltammetry

Spectroelectrochemistry of Vanadium Acetylacetonate and Chromium Acetylacetonate for Symmetric Nonaqueous Flow Batteries

“…This would entail reducing a Cr[III] complex to Cr[I] while oxidizing another Cr[III] complex to Cr[VI], which is unlikely: examinations of the first reduction of Cr(acac) 3 on various electrodes and in various supporting solutions have not yielded any reports of multiple-electron first reductions. 13,15,[17][18][19][20] Additionally, a mechanism where the Cr[III] complex oxidized to Cr[VI] would be anomalous in light of the responses of other M(acac) 3 complexes, which appear consistent with single-electron oxidations. 2,9,28 Both dimerization of the complex or the chromium within it and ligand-dissociation processes allow mechanisms consistent with Equation 3 in which b/d = 2/3.…”

“…Reaction 7) would consequently depend strongly on solvent choice, which could explain the widely variable reduction responses of Cr(acac) 3 observed in literature. [13][14][15][17][18][19][20] Studies of solvent compatibility for RFB applications similar to those performed earlier with V(acac) 3 41,42 could therefore be fruitful, and are ongoing. …”

“…The electrochemical response during reduction depends heavily upon solvent, with different behavior observed in dimethylsulfoxide, 13,15,18,19 N,N-dimethylformamide, 15 dichloromethane, 14 acetonitrile, 15,17,20 and others. 15 Various mechanisms have been proposed for the first reduction, but the first oxidation mechanism has only received significant attention since Cr(acac) 3 was proposed for nonaqueous RFB applications.…”

“…Experimental efforts to clarify the electrochemistry of Cr(acac) 3 have been challenging because the reaction mechanism apparently varies with the choices of solvent, supporting electrolyte, and working electrode. [13][14][15][16][17] The literature describing nonaqueous Cr(acac) 3 electrochemistry does not provide a consensus about the mechanisms for either the first reduction or first oxidation of the neutral complex. The electrochemical response during reduction depends heavily upon solvent, with different behavior observed in dimethylsulfoxide, 13,15,18,19 N,N-dimethylformamide, 15 dichloromethane, 14 acetonitrile, 15,17,20 and others.…”

“…[13][14][15][16][17] The literature describing nonaqueous Cr(acac) 3 electrochemistry does not provide a consensus about the mechanisms for either the first reduction or first oxidation of the neutral complex. The electrochemical response during reduction depends heavily upon solvent, with different behavior observed in dimethylsulfoxide, 13,15,18,19 N,N-dimethylformamide, 15 dichloromethane, 14 acetonitrile, 15,17,20 and others. 15 Various mechanisms have been proposed for the first reduction, but the first oxidation mechanism has only received significant attention since Cr(acac) 3 was proposed for nonaqueous RFB applications.…”