Chemistry of Cobalt Acetate. 7. Electrochemical Oxidation of μ₃-Oxo-Centered Cobalt(III) Acetate Trimers

Abstract

Electrochemical and spectroelectrochemical properties of five cobalt(III) acetate complexes [CoIII3(mu3-O)(CH3CO2)5(OR)(py)3][PF6] are described, where py=pyridine and R=OCCH3 (A), H (B), CH3 (C), CH2CH=CH2 (D), and CH2C6H5 (E). Each is reduced irreversibly as observed by cyclic voltammetry at room temperature and at -40 degrees C in acetonitrile at scan rates up to 20 V s(-1), but oxidized reversibly to a mixed-valence Co(III)2Co(IV) species at approximately 1.23 V vs the ferrocenium/ferrocene couple. Controlled potential coulometry confirmed a one-electron-oxidation process. Spectroelectrochemical oxidation of A at 5 degrees C showed isosbestic points in the electronic absorption spectrum that showed the oxidized complex to be stable in solution for at least 1 h.

A Synthetic Approach to Trinuclear Cluster with [Co3(μ3‐O)(μ‐OH)] Core: A Comparative Study on Cluster having [Co3(μ3‐O)(μ‐OH)] and [Co4(μ3‐O)4] Core

“…Beattie et al [14] have reported a similar type of electrochemical behavior on structurally related complex [Co 3 (μ 3 -O)(μ-OH)(μ-OAc) 5 (py) 3 ]. The peak to peak difference responsible for the Co(III)-Co(IV) redox couple observed at a slow scan rate of 20 mVs À 1 is 197 mV for complex 1 with E 1/2 = 0.82 V. At a high scan rate the ΔE p for the redox process remains almost the same with i pc /i pa~1 .…”

Molecular Cobalt Clusters as Precursors of Distinct Active Species in Electrochemical, Photochemical, and Photoelectrochemical Water Oxidation Reactions in Phosphate Electrolytes

“…Co‐trimer has been shown to undergo a reversible one‐electron oxidation in acetonitrile/TBAH at +1.66 V 9. Solutions of Co‐trimer in electrolyte I exhibit a catalytic process centered at approximately 1.3 V, as shown in Figure 1 c.This catalytic process could be quenched by the addition of Na 2 EDTA, as shown in Figure S5 (Supporting Information), indicating that the catalytic electron transfer at around 1.3 V is probably attributable to the presence of a Co II species, which can be sequestered by addition of Na 2 EDTA.…”

“…Co-trimer has been shown to undergo ar eversible one-electron oxidation in acetonitrile/TBAH at + 1.66 V. [9] Solutions of Co-trimer in electrolyte Ie xhibit ac atalytic process centered at approximately 1.3 V, as shown in Figure 1c.This catalytic process couldb eq uenched by the addition of Na 2 EDTA, as shown in Figure S5 (Supporting Information), indicating that the cata- lytic electron transfer at around 1.3 Vi sp robably attributable to the presence of aC o II species, which can be sequestered by addition of Na 2 EDTA. Therefore, the estimated Co II concentration detected in the CV experiments was determined, in order to excludet he possibility that the Co II species detected during these experiments of the Co-trimer stems from an impurity.…”

Effect of solvent on the construction of Co(II) coordination polymers containing a semi-rigid bis(benzimidazole) derivative: syntheses, structures, and properties

“…Design and construction of metal-organic coordination polymers (CPs) have been studied for intriguing architectures and topologies [1], potential applications in luminescence [2], electrochemistry [3], and gas storage [4]. Various effective strategies for synthesis of CPs, such as tuning inorganic anions [5], organic ligands [6], pH values [7], templates and solvent effects [8], as well as hydrothermal [9], in situ [10], and ionothermal syntheses [11], have been well documented.…”