Oxygen atom transfer mediated by an iron(IV)/iron(II) macrocyclic complex containing pyridine and tertiary amine donors

Exceedingly Fast Oxygen Atom Transfer to Olefins via a Catalytically Competent Nonheme Iron Species

“…With these limitations in mind, 2 can be ranked among the different types of iron–oxygen species for which second‐order reaction rates for OAT reactions have been determined (Table , Figure ). The iron(IV) oxo complexes 3 and 4 , bearing pyridine‐containing macrocyclic ligands, and 5 with a N 2 S 2 thioether ligand exhibit rates that are three to four orders of magnitude lower than 2 , but these reactions were carried out at much higher temperatures. The same difference in reactivity was observed for the iron(IV) oxo complex 6 , which bears a pentadentate N4Py ligand, in the presence of triflic acid .…”

Catalytic Applications of Pyridine‐Containing Macrocyclic Complexes

“…All experimental evidence provided by Costas and co‐workers was in agreement with complex 15 being the active species in oxygen atom transfer (OAT) with alkenes. Active species 15 exhibited rates in OAT reactions with cyclooctene three to four orders of magnitude higher than those reported for the ferryl(IV) intermediates of ligands 10 and 11 . A Co II analogue of 14 (perchlorate salt) was recently reported .…”

“…The Rybak‐Akimova group more recently showed that N ‐alkylated macrocyclic tetradentate ligand 10 (Figure ) was much more stable than 7b . Depending on the coordinating abilities of the chosen anion, Fe II complexes of ligand 10 adopted either a distorted octahedral geometry, with weakly bonded cis ‐triflate molecules, or a distorted square‐pyramidal geometry, with a more strongly coordinating chloride ion in the axial position . N ‐Alkylation of the macrocyclic ligand caused a change in the spin state of the coordinated iron(II) ion, favouring a high‐spin configuration, resulting in a lower catalytic activity (only a 7 % yield in the epoxidation of cyclooctene with H 2 O 2 as terminal oxidant; TON = 1, in the absence of externally added mineral acid).…”

Synthesis and crystal structure of [2,7,12-trimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-triene-κ4N]copper(II) bis(perchlorate)

“…1) being most active (Organo et al, 2009). Fe was also found to have catalytic use in epoxidation reactions of cyclooctene with hydrogen peroxide (Ye et al, 2012). A similar Cu II -PyMAC complex but without methyl groups at the macrocyclic ring was reported by Fernandes et al (2007) to scavenge superoxide.…”