Chemical oscillation of vanadium complexes: Simple and aperiodic systems

An oscillatory chemical reaction is an intriguing phenomenon subject to various and often uncontrollable factors. Many oscillatory systems consist of a strong acid, metal ion and an additional species with accessible oxidation states, and restrictive temperature conditions. Thus, an oscillatory system in which all the factors are understood would be useful. In this paper, we describe the first such system based on vanadium chemistry. The V(IV) complex (pale green color) turns dark orange with the production of a V(V) complex. This reaction is affected by many factors such as oxygen, ultraviolet (UV) irradiation, visible irradiation, and aldehyde addition. This oscillation reaction occurs only in a dichloromethane solution, suggesting that the solvent intervenes in the reaction. Examination of the gas phase during the oscillation reaction revealed the formation of carbon monoxide, carbon dioxide, hydrogen chloride, and phosgene. Based on these observations, we propose a plausible oscillation reaction mechanism.The results of this study contribute to the field of nonlinear dynamics. Additionally, this work offers new insights into vanadium chemistry because this oscillation phenomenon is strongly correlated with the electron transfer reaction of the vanadium complex. Moreover, studies using vanadium complexes may help in understanding vanadium-mediated electron transfer systems in vivo, such as vanadium accumulation and storage observed in marine organisms.

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