Redox-active organic molecules are promising charge-storage materials for redox-flow batteries (RFBs), but material crossover between the posolyte and negolyte and chemical degradation are limiting factors in the performance of all-organic RFBs. We demonstrate that the bipolar electrochemistry of 1,2,4-benzotriazin-4-yl (Blatter) radicals allows the construction of batteries with symmetrical electrolyte composition. Cyclic voltammetry shows that these radicals also retain reversible bipolar electrochemistry in the presence of water. The redox potentials of derivatives with a C(3)-CF 3 substituent are the least affected by water, and moreover, these compounds show >90% capacity retention after charge/discharge cycling in a static H-cell for 7 days (ca. 100 cycles). Testing these materials in a flow regime at a 0.1 M concentration of the active material confirmed the high cycling stability under conditions relevant for RFB operation and demonstrated that polarity inversion in a symmetrical flow battery may be used to rebalance the cell. Chemical synthesis provides insight in the nature of the charged species by spectroscopy and (for the oxidized state) X-ray crystallography. The stability of these compounds in all three states of charge highlights their potential for application in symmetrical organic redox-flow batteries.

Reductive elimination is an elementary organometallic reaction step involving a formal oxidation state change of −2 at a transition‐metal center. For a series of formal high‐valent NiIV complexes, aryl–CF3 bond‐forming reductive elimination was reported to occur readily (Bour et al. J. Am. Chem. Soc. 2015, 137, 8034–8037). We report a computational analysis of this reaction and find that, unexpectedly, the formal NiIV centers are better described as approaching a +II oxidation state, originating from highly covalent metal–ligand bonds, a phenomenon attributable to σ‐noninnocence. A direct consequence is that the elimination of aryl–CF3 products occurs in an essentially redox‐neutral fashion, as opposed to a reductive elimination. This is supported by an electron flow analysis which shows that an anionic CF3 group is transferred to an electrophilic aryl group. The uncovered role of σ‐noninnocence in metal–ligand bonding, and of an essentially redox‐neutral elimination as an elementary organometallic reaction step, may constitute concepts of broad relevance to organometallic chemistry.

Selection of the optimum conditions for the vulcanization of rubber products, particularly of bulky ones, often is quite difficult. Especially in cases of high demand, it is unavoidable to destruct expensive prototypes in order to check important properties of the rubber at various locations throughout the product. Finite element calculations can be used to predict the flow of heat during the vulcanization process. By converting the total heat input at a selected location during a certain time into a so‐called “effective vulcanization time” at a fixed reference temperature, it becomes possible to predict the properties of the rubber at that location. An example of such a procedure is given. However, to secure optimum conditions in this way would require repetitive (expensive) calculations. In this article a method is developed in which the vulcanization conditions are derived from the required properties of the rubber compound. The idea behind it is that optimal vulcanization is reached when at each location within the rubber product the effective vulcanization time at a selected reference temperature lies within predefined limits. The choice of the limits can be derived from the dependence of each of the properties chosen on the vulcanization time at the reference temperature.

Redox flow batteries based on organic electrolytes are promising energy storage devices, but stable long‐term cycling is often difficult to achieve. Bipolar organic charge‐storage materials allow the construction of symmetrical flow batteries (i. e., with identical electrolyte composition on both sides), which is a strategy to mitigate crossover‐induced degradation. One such class of bipolar compounds are verdazyl radicals, but little is known on their stability/reactivity either as the neutral radical, or in the charged states. Here, we study the chemical properties of a Kuhn‐type verdazyl radical (1) and the oxidized/reduced form (1+/−). Chemical synthesis of the three redox‐states provides spectroscopic characterization data, which are used as reference for evaluating the composition of the electrolyte solutions of an H‐cell battery during/after cycling. Our data suggest that, rather than the charged states, the decomposition of the parent verdazyl radical is responsible for capacity fade. Kinetic experiments and DFT calculations provide insight in the decomposition mechanism, which is shown to occur by bimolecular disproportionation to form two closed‐shell products (leuco‐verdazyl 1H and triazole derivative 2).

Reductive elimination is an elementary organometallic reaction step involving aformal oxidation state change of À2a tatransition-metal center.F or as eries of formal highvalent Ni IV complexes,a ryl-CF 3 bond-forming reductive elimination was reported to occur readily (Bour et al. J. Am. Chem. Soc. 2015,137, 8034-8037). We report acomputational analysis of this reaction and find that, unexpectedly,the formal Ni IV centers are better described as approaching a + II oxidation state,o riginating from highly covalent metal-ligand bonds,aphenomenon attributable to s-noninnocence.Adirect consequence is that the elimination of aryl-CF 3 products occurs in an essentially redox-neutral fashion, as opposed to ar eductive elimination. This is supported by an electron flow analysis which shows that an anionic CF 3 group is transferred to an electrophilic aryl group.T he uncovered role of s-noninnocence in metal-ligand bonding,and of an essentially redox-neutral elimination as an elementary organometallic reaction step,m ay constitute concepts of broad relevance to organometallic chemistry.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.org/10.