Allylic Peroxidations with Bis(2‐pyridylimino)isoindolato‐Cobalt and ‐Iron Complexes

Abstract

Several novel substituted bis(2‐pyridylimino)isoindolato (BPI) cobalt(II) and iron(II) complexes [M(BPI)(OAc)(H2O)] (M = Co: 1 ‐ 6, Fe: 7) have been synthesized by reaction of bis(2‐pyridylimino)isoindole derivatives with the corresponding metal(II) acetates. Reaction of 1‐6 with 1.5 ‐ 2 molar equivalents of t‐BuOOH gave the corresponding alkylperoxocobalt(III) complexes [Co(BPI)(OAc)(OOtBu)] (10 ‐ 15). Using an aqueous solution of t‐BuOOH (70 %), cyclohexene was selectively catalytically oxidized to the dialkylperoxide cyclohex‐2‐ene‐1‐t‐butylperoxide.

Isoindoline-derived ligands and applications

“…The first steps towards perfect homogenous catalysts required additional reactants. 61,88 Selectivity towards the desired product was reported to be outstanding. 74 By the right metal ion choice stable hydoperoxo intermediates have been characterized with cobalt (67) and used in hydrocarbon hydroxylation, oxidation.…”

Redox properties of cobalt(II) complexes with isoindoline-based ligands

“…Terpyridines [1], bis-(N-arylimino)isoindolines (BAI, or indH) [2], and tripyrrins (Trpy) [3] are built-up on rigid p-conjugated frameworks that favor meridional coordination. In addition, with respect to the isoindoline-based ligands, two tridentate binding modes have been demonstrated: in some cases, the ligand is neutral and bears an exocyclic amine function (Scheme 1, forms A and C) [4][5][6][7][8][9], whereas in the majority of the known complexes the isoindoline nitrogen of form B (Scheme 1) is deprotonated resulting a monoanionic ligand with two imine functions [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. BAIs form stable complexes with cobalt that exhibit remarkable reactivities.…”

“…BAIs form stable complexes with cobalt that exhibit remarkable reactivities. When cobalt(II) acetate adopts a bis-(N-arylimino)isoindolinate ligand the resulting complex catalyzes the conversion of cyclohexylhydroperoxide to cyclohexanone and cyclohexanol [12,13], or that of cyclohexene to the corresponding dialkylperoxide [16,18]. Another mixed-ligand complex containing acetylacetonate was applied in radical polymerization of acrylates [22].…”

New Chemistry with Anionic NNN Pincer Ligands

“…The reactions were found to give a mixture of oxidized products: cyclohex-2-ene-1-tert-butylperoxide, cyclohex-2-en-1-one, cyclohex-2-en-1-ol, and epoxycyclohexane [118]. Improved selectivity was observed; however, if the temperature of the reaction was controlled and a 70% aqueous solution of t BuOOH was used, cyclohex-2-ene-1-tert-butylperoxide was formed selectively (Scheme 28).…”