Syntheses, structures and catalytic activities of dinuclear copper complexes with tetradentate diaminebis (phenolate) ligands

Mn(III)‐salan/graphene oxide/magnetite nanocomposite as a highly selective catalyst for aerobic epoxidation of olefins

“…The salen was synthesized from 5‐chloromethyl‐2‐hydroxybenzaldehyde and trans ‐(±)‐1,2‐diaminocyclohexane in a 2:1 ratio. Reduction of the imine functionalities of the compound with four equimolar amounts of sodium borohydride resulted in the formation of product salan (Scheme ) . Salan is potentially a chelating tetradentate dianionic ligand and could coordinate to metal centres by N 2 O 2 atoms.…”

“…For the synthesis of salan (H 2 [H 4 ]L; N , N ′‐bis(2‐hydroxy‐5‐chloromethylbenzyl)‐1,2‐diaminocyclohexane), sodium borohydride (0.23 g, 6.15 mmol) was added slowly within 30 min to a solution of salen (0.645 g, 1.50 mmol) in methanol (15 ml). The mixture was stirred for 1 h at room temperature and then refluxed for 4 h. The resulting yellow solid product was filtered off, washed with methanol (4 × 1 ml) and dried at room temperature . Yield: 89% (0.57 g).…”

“…The mixture was stirred for 1 h at room temperature and then refluxed for 4 h. The resulting yellow solid product was filtered off, washed with methanol (4 × 1 ml) and dried at room temperature. [19] Yield: 89% (0.57 g).…”

“…Reduction of the imine functionalities of the compound with four equimolar amounts of sodium borohydride resulted in the formation of product salan (Scheme 1). [19] Salan is potentially a chelating tetradentate dianionic ligand and could coordinate to metal centres by N 2 O 2 atoms. The Mn(III) complex of the salan ligand was prepared by treating a CH 2 Cl 2 solution of salan with MnCl 2 Á4H 2 O. As-synthesized Mn-salan was supported on GFC via covalent attachment (Scheme 1).…”

“…Non‐planar metal–salan complexes were found to exert unprecedented asymmetric catalysis . Our group has synthesized dinuclear complexes of Cu(II) with tetradentate salan ligands and used them for the epoxidation of olefins with H 2 O 2 . Hydrogen bonding of the coordinated hydrogen peroxide with the adjacent amino proton probably prevents the non‐productive dismutation of H 2 O 2 .…”