Complexes of N,N′,N′′-tris(2-hydroxypropyl)-1,4,7-triazacyclononane (L): Structures of [CuL](ClO4)(NO3), [CoL](ClO4)2, [ZnL](ClO4)2 and the catalytic activity of [MnL](ClO4)2 towards olefin epoxidation with hydrogen peroxide

Abstract

Complexes of N,N′,N′′-tris(2-hydroxypropyl)-1,4,7-triazacyclononane (L), [CuL](ClO4)(NO3) (1), [CoL](ClO4)2 (2), [ZnL](ClO4)2 (3) and [MnL](ClO4)2 (4), have been synthesized and characterized on the basis of elemental analysis, electrospray ionization mass spectrometry, UV–Vis measurements and cyclic voltammetry. Crystal structures of the former three complexes, characterized by X-ray crystallography, show that these complexes are monoclinic with space group P21/n and P21/c. Each metal central in the complexes is six-coordinate with three N atoms of the macrocycle and three O atoms from the pendant hydroxypropyl arms, forming a distorted octahedral configuration. [MnL](ClO4)2 (4) is employed as catalyst in olefin epoxidation with H2O2. The final results indicate that complex (4) has good catalytic activity towards olefin epoxidation. Under mild conditions, the olefin conversion is moderate and epoxidation selectivity is 95–100%.