Diiron(III) oxo-bridged complexes with BPMEN and additional monodentate or bidentate ligands: Synthesis and reactivity in olefin epoxidation with H2O2

2‐Amino‐4‐(2‐pyridyl)thiazole as Chelating Ligand: A Dinuclear Oxido‐Bridged Ferric Complex and Mononuclear 3d Metal Complexes

“…A small trans influence is observed with Fe III –N py distances trans to the oxido‐bridge being somewhat longer [2.267(3)–2.290(5) Å] than those trans to the F – ions [2.170(3)–2.180(6) Å]. The Fe III –F distances [1.893(2)–1.918(2) Å] are comparable to those of the difluorido complexes of bpmen [1.843(3) Å]48 and TPyA [1.849(2), 1.892(2) Å] 49. Intramolecular π–π stacking is observed in both complexes of 1· solvent between the pyridyl ring trans to the fluorido co‐ligand and the thiazole ring of the corresponding ligand of the neighbouring half molecule.…”

“…In the two other complexes with a [Fe III N 4 F(μ‐O)FN 4 Fe III ] entity published so far, namely [(bpmen)FFe III (μ‐O)Fe III F(bpmen)](ClO 4 ) 2 48 and [(TPyA)FFe III (μ‐O)Fe III F(TPyA)](BF 4 ) 2 ,49 a trans coordination with respect to the Fe–O–Fe moiety is found [bpmen and TPyA are the tetradentate N 4 ligands N , N′ ‐dimethyl‐ N , N′ ‐bis(2‐pyridylmethyl)ethane‐1,2‐diamine and tris(2‐pyridylmethyl)amine, respectively]. In similar complexes of bpmen with other monodentate co‐ligands such as chloride,50,51 acetate48 or fluoride/acetate,48 or of TPyA and chloride,52 these are also usually coordinated trans with respect to the Fe–O–Fe moiety. A similar staggered coordination of the co‐ligands, however, is found in the similar oxido‐bridged ferric complexes [(L) 2 ClFe III (μ‐O)Fe III Cl(L) 2 ] 2+ (L = 2,2′‐bipyridine53 or 4,4′‐dimethyl‐2,2′‐bipyridine) 54.…”

“…A similar staggered coordination of the co‐ligands, however, is found in the similar oxido‐bridged ferric complexes [(L) 2 ClFe III (μ‐O)Fe III Cl(L) 2 ] 2+ (L = 2,2′‐bipyridine53 or 4,4′‐dimethyl‐2,2′‐bipyridine) 54. The Fe–O–Fe moiety in 1· 1.25MeOH [157.7(1)°] and 1· MeCN [156.9(3)°] is unusually bent compared with the complexes of bpmen,48,50,51 TPyA,49,52 2,2′‐bipyridine53 or 4,4′‐dimethyl‐2,2′‐bipyridine54 mentioned previously, but is within the range found for other Fe–O–Fe‐bridged complexes 39,42. The Fe–O distances [1.825(2), 1.815(2) and 1.819(4), 1.806(4)° for 1· 1.25MeOH and 1· MeCN, respectively] are characteristic of singly oxido‐bridged ferric complexes 39,42.…”

Equilibrating (L)FeIII–OOAc and (L)FeV(O) Species in Hydrocarbon Oxidations by Bio-Inspired Nonheme Iron Catalysts Using H2O2 and AcOH

“…Indeed ESI-MS analysis of the reaction mixture at the end of the reaction shows the major decay product to be [(TPA*) 2 Fe III 2 (μ-O)(μ-OAc)] 3+ (Figure S13), which possesses an absorption maximum at ~460 nm 81, 82 and has been shown to be catalytically inactive towards the substrates tested in this study. 34, 83 …”

The Active Intermediates of Non‐Heme‐Iron‐Based Systems for Catalytic Alkene Epoxidation with H2O2/CH3COOH

“…Very recently, it has been shown that binuclear iron(III)-BPMEN complexes are less active in epoxidation with H 2 O 2 than mononuclear complex 1 under the same conditions. [31] This result argues against the involvement of a binuclear intermediate in the 1/H 2 O 2 system. On the other hand, the diiron complex with dinucleating, covalently linked TPA derivatives confirms the high reactivity of oxo-bridged diiron(III) species in olefin epoxidation.…”