Enhanced Alkene Oxidative Cleavage in Water via Photoexcited FeIV Species within Covalent Organic Framework Thin Films.

The oxidative cleavage of alkenes is a crucial step in synthesizing key organic molecules featuring carbonyl functional groups prevalent in natural products and pharmaceuticals. We introduce a photochemical method for heterogeneous C=C bond cleavage, employing photo-catalytically generated [(bTAML)Fe-O-Fe(bTAML)] species (where bTAML stands for biuret-modified tetraamido macrocyclic ligand) in aqueous environments under gentle conditions. Leveraging the photosensitizing properties of Covalent Organic Frameworks (COFs) and their advantageous morphological traits as films, we enhance the reaction by closely associating the substrate with the catalyst.

Proton-assisted activation of a Mn-OOH for aromatic C-H hydroxylation through a putative [MnO] species.

Adding HClO to [(BnTPEN)Mn-OO] in MeOH generates a short-lived Mn-OOH species, which converts to a putative MnO species. The potent MnO species in MeCN oxidizes the pendant phenyl ring of the ligand in an intramolecular fashion. The addition of benzene causes the formation of (BnTPEN)Mn-phenolate.

A tale of two topological isomers: Uptuning [Fe(O)(Mecyclam)] for olefin epoxidation.

TMC- and TMC- the two topological isomers of [Fe(O)(TMC)(CHCN)] (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, or Mecyclam), differ in the orientations of their Fe=O units relative to the four methyl groups of the TMC ligand framework. The Fe=O unit of TMC- points away from the four methyl groups, while that of TMC- is surrounded by the methyl groups, resulting in differences in their oxidative reactivities. TMC- reacts with HAT (hydrogen atom transfer) substrates at 1.

Formation of a Reactive [Mn(III)-O-Ce(IV)] Species and its Facile Equilibrium with Related Mn(IV)(OX) (X = Sc or H) Complexes.

Lewis acid-bound high valent Mn-oxo species are of great importance due to their relevance to photosystem II. Here, we report the synthesis of a unique [(BnTPEN)Mn(III)-O-Ce(IV)(NO ) ] adduct (2) by the reaction of (BnTPEN)Mn(II) (1) with 4 eq. ceric ammonium nitrate.

Proximity-Enabled Photochemical C-H Functionalization using a Covalent Organic Framework-Confined Fe-μ-oxo Species in Water.

Water has been recognized as an excellent solvent for maneuvering both the catalytic activity and selectivity, especially in the case of heterogeneous catalysis. However, maintaining the active catalytic species in their higher oxidation states (IV/V) while retaining the catalytic activity and recyclability in water is an enormous challenge. Herein, we have developed a solution to this problem using covalent organic frameworks (COFs) to immobilize the (EtN)[Fe(Cl)bTAML] molecules, taking advantage of the COF's morphology and surface charge.

Electrocatalytic alcohol oxidation by a molecular iron complex.

An efficient electrochemical method for the selective oxidation of alcohols to their corresponding aldehydes/ketones using a biomimetic iron complex, [(bTAML)Fe-OH], as the redox mediator in an undivided electrochemical cell with inexpensive carbon and nickel electrodes using water as an oxygen source is reported. The substrate scope also includes alcohols that contain O and N heteroatoms in the scaffold, which are well tolerated under these reaction conditions. Mechanistic studies show the involvement of a high-valent Fe(O) species, [(bTAML)Fe(O)], formed PCET (overall 2H/2e) from [(bTAML)Fe-OH] at 0.

Oxoiron(v) mediated selective electrochemical oxygenation of unactivated C-H and C[double bond, length as m-dash]C bonds using water as the oxygen source.

An efficient electrochemical method for the selective oxidation of C-H bonds of unactivated alkanes (BDE ≤97 kcal mol) and C[double bond, length as m-dash]C bonds of alkenes using a biomimetic iron complex, [(bTAML)Fe-OH], as the redox mediator in an undivided electrochemical cell with inexpensive carbon and nickel electrodes is reported. The O-atom of water remains the source of O-incorporation in the product formed after oxidation. The products formed upon oxidation of C-H bonds display very high regioselectivity (75 : 1, 3° : 2° for adamantane) and stereo-retention (RC ∼99% for cyclohexane derivatives).

Heterogeneous C-H Functionalization in Water via Porous Covalent Organic Framework Nanofilms: A Case of Catalytic Sphere Transmutation.

Heterogeneous catalysis in water has not been explored beyond certain advantages such as recyclability and recovery of the catalysts from the reaction medium. Moreover, poor yield, extremely low selectivity, and active catalytic site deactivation further underrate the heterogeneous catalysis in water. Considering these facts, we have designed and synthesized solution-dispersible porous covalent organic framework (COF) nanospheres.

Selective oxygenation of unactivated C-H bonds by dioxygen via the autocatalytic formation of oxoiron(v) species.

Selective catalytic oxygenation of unactivated C-H bonds for a series of substrates by dioxygen using iron complexes was performed without the use of a co-reductant. Mechanistic studies indicate that the reaction proceeded via the autocatalytic formation of an oxoiron(v) intermediate, which brings high regioselectivity and stereoretention.

Selective photocatalytic hydroxylation and epoxidation reactions by an iron complex using water as the oxygen source.

The iron complex [(bTAML)Fe-OH] () selectively catalyses the photocatalytic hydroxylation and epoxidation reactions of alkanes and alkenes, respectively, using water as the oxygen-atom source. Upon the oxidation of unactivated alkanes, which included several substrates including natural products, hydroxylation was observed mostly at the 3° C-H bonds with 3° : 2° selectivity up to ∼100 : 1. When alkenes were used as the substrates, epoxides were predominantly formed with high yields.