Oxidation of Cyclohexane by a High-Valent Iron Bispidine Complex: A Combined Experimental and Computational Mechanistic Study

Abstract

Experimental data suggest that there are various competing pathways for the catalytic and stoichiometric oxygenation of cyclohexane, assisted by iron-bispidine complexes and using various oxidants (H(2)O(2), O(2), PhIO). Density functional theory calculations indicate that both Fe(IV)=O and Fe(V)=O species are accessible and efficiently transfer their oxygen atoms to cyclohexane. The reactivities of the two isomers each and the two possible spin states for the Fe(IV)=O and Fe(V)=O species are sufficiently different to allow an interpretation of the experimental data.

Synthesis, Structure, and Highly Efficient Copper‐Catalyzed Aziridination with a Tetraaza‐Bispidine Ligand

“…[30] The majority of bispidine ligands reported so far has two or more aromatic nitrogen donor groups and enforces coordination geometries derived from cis octahedral with metal-donor distances and angular geometries around the metal center strictly enforced by the rigid adamantanoid bispidine backbone. Although complexes with specifically distorted cis-octahedral geometries, imposed by the first-generation bispidine ligands, for example, L 2 , have produced exciting results, [30,31] specifically in the areas of ligand-enforced molecular geometries and the emerging properties, [32][33][34][35] and metal-ion-mediated oxygen activation, [36][37][38][39][40] we have designed a similarly rigid ligand system that may impose different coordination geometries to the metal center and offer a large variety of donor sets. We report here the first example of a second generation of bispidine ligands (L 1 versus L 2 ), in which the extra donors are exclusively due to substitution at the amine components of the Mannich reaction.…”

Iron-catalysed oxidation and halogenation of organic matter in nature

“…3), [57,88,101,119] and the mechanism of olefin epoxidation and dihydroxylation has been studied, both experimentally and by quantum-chemical methods. [120,121] Careful product analyses, including 18 Fig. 5, and these were confirmed by DFT calculations.…”

“…Several the thoroughly studied reactions with bispidine-ferryl complexes are shown in Fig. 15 (epoxidation and cis-dihydroxylation of alkenes, [84,121] oxidation [92,120] and halogenation [89] of cyclohexane, sulfoxidation [116] and catechol oxidation [113] ). Although these earlier mechanistic studies were generally performed in organic Fig.…”

“…Cl À or a species derived from H 2 O, e.g. OH À ): (1) olefin epoxidation and cis-dihydroxylation, [84,121] (2) cyclohexane oxidation, [92,120] and (3) halogenation, [89,118] (4) sulfoxidation, [116] (5) catechol oxidation [113] and (6) furan formation. [169] …”

Elektronentransfereigenschaften eines effizienten Nichthäm‐ Eisenkatalysators mit einem vierzähnigen Bispidinligand

“…[19][20][21][22][23] Computerchemische Studien der Bispidin-Fe IV = OSpezies zeigen eine sehr kleine Energielücke zwischen den Intermediate-Spin-(S = 1) und High-Spin-Konfigurationen (S = 2). [21][22][23] {E ox = 0.69 V}) [10] …”