Correction: Lewis acid improved dioxygen activation by a non-heme iron(II) complex towards tryptophan 2,3-dioxygenase activity for olefin oxygenation.

Correction for 'Lewis acid improved dioxygen activation by a non-heme iron(II) complex towards tryptophan 2,3-dioxygenase activity for olefin oxygenation' by Guangjian Liao et al., Dalton Trans., 2022, https://doi.org/10.1039/d2dt02769k.

Lewis acid improved dioxygen activation by a non-heme iron(II) complex towards tryptophan 2,3-dioxygenase activity for olefin oxygenation.

Dioxygen activation and catalysis around ambient temperature is a long-standing challenge in chemistry. Inspired by the significant roles of the hydrogen bond network in dioxygen activation and catalysis by redox enzymes, this work presents a Lewis acid improved dioxygen activation by an FeII(BPMEN)(OTf)2 complex towards tryptophan 2,3-dioxygenase (TDO) activity for 3-methylindole and common olefinic CC  bond oxygenation and cleavage (enzymatic Brønsted acid vs. chemical Lewis acid). It was found that the presence of a Lewis acid such as Sc3+ could substantially improve olefinic CC  bond oxygenation and cleavage activity through FeII(BPMEN)(OTf)2 catalyzed dioxygen activation. Notably, a more negative ρ value in the Hammett plot of para-substituted styrene oxygenations was observed in the presence of a stronger Lewis acid, disclosing the enhanced electrophilic oxygenation capability of the putative iron(III) superoxo species through its electrostatic interaction with a stronger Lewis acid. Thereof, this work has demonstrated a new strategy in catalyst design for dioxygen activation and catalysis for olefin oxygenation, a significant process in the chemical industry.

Bifunctional Solid Catalyst for Organic Reactions in Water: Simultaneous Anchoring of Acetylacetone Ligands and Amphiphilic Ionic Liquid "Tags" by Using a Dihydropyran Linker.

The use of solid catalysts to promote organic reactions in water faces the inherent difficulty of the poor mass-transfer efficiency of organic substances in water, which is often responsible for insufficient reaction and low yields. To solve this problem, the solid surface can be manipulated to become amphiphilic. However, the introduction of surfactant-like moieties onto the surface of silica-based materials is not easy. By using an accessible dihydropyran derivative as a grafting linker, a surfactant-combined bifunctional silica-based solid catalyst that possessed an ionic liquid tail and a metal acetylacetonate moiety was prepared through a mild Lewis-acid-catalyzed ring-opening reaction with a thiol-functionalized silica. The surfactant-combined silica-supported metal acetylacetone catalysts displayed excellent catalytic activity in water for a range of reactions. The solid catalyst was also shown to be recyclable, and was reused several times without significant loss in activity.

Lewis-acid-promoted stoichiometric and catalytic oxidations by manganese complexes having cross-bridged cyclam ligand: a comprehensive study.

Redox-inactive metal ions have been recognized to be able to participate in redox metal-ion-mediated biological and chemical oxidative events; however, their roles are still elusive. This work presents how the redox-inactive metal ions affect the oxidative reactivity of a well-investigated manganese(II) with its corresponding manganese(IV) complexes having cross-bridged cyclam ligand. In dry acetone, the presence of these metal ions can greatly accelerate stoichiometric oxidations of triphenylphosphine and sulfides by the manganese(IV) complexes through electron transfer or catalytic sulfoxidations by the corresponding manganese(II) complexes with PhIO. Significantly, the rate enhancements are highly Lewis-acid strength dependent on added metal ions. These metal ions like Al(3+) can also promote the thermodynamic driving force of the Mn(IV)-OH moiety to facilitate its hydrogen abstraction from ethylbenzene having a BDE(CH) value of 85 kcal/mol, while it is experimentally limited to 80 kcal/mol for Mn(IV)-OH alone. Adding Al(3+) may also improve the manganese(II)-catalyzed olefin epoxidation with PhIO. However, compared with those in electron transfer, improvements in hydrogen abstraction and electron transfer are minor. The existence of the interaction between Lewis acid and the manganese(IV) species was evidenced by the blue shift of the characteristic absorbance of the manganese(IV) species from 554 to 537 nm and by converting its EPR signal at g = 2.01 into a hyperfine 6-line signal upon adding Al(3+) (I = 5/2). Cyclic voltammograms of the manganese(IV) complexes reveal that adding Lewis acid would substantially shift its potential to the positive direction, thus enhancing its oxidizing capability.

Redox inactive metal ion promoted C-H activation of benzene to phenol with Pd(II)(bpym): demonstrating new strategies in catalyst designs.

Al in: A new strategy was introduced to modify the electronics and steric hindrance of the Pd(II) ion in order to change its reactivity towards benzene hydroxylation. In trifluoroacetic acid, free Pd(II) ions provide dominantly biphenyl, with phenol as minor product. Ligation of bpym to the Pd(II) ion results in its deactivation with regard to benzene functionalization. The addition of the redox inactive Al(III) ion to the Pd(II)(bpym) complex recovers its catalytic activity, and alters the reactivity of Pd(II) ion from benzene coupling to hydroxylation.