Template synthesis, characterization and catalytic behaviour of oxovanadium(IV) macro cyclic complexes

Abstract

The oxovanadium(IV )-directed condensation of 2,4- pentane dione with diamines [ethylenediamine(a), 1,2- diaminopropane(b), 1,3-diaminopropane(c) and <i>o- </i>phenylenediamine(d)] in ethanol produces macrocyclic complexes of the type [VO(L)(SO₄)].3H₂O [<b>1a-1d</b>] in high yields. The complexes have been characterized by elemental analyses, conductance measurements, IR, electronic and ESR spectra. They act as active catalysts at room temperature for olefin epoxidation in the presence of <i>t</i>-butylhydroperoxide(TBHP). Norbornene gives exo epoxide. Competitive epoxidation of cycloolefins follows the order: norbornene > cyclohexene. The anionic surfactants (SLS) promote epoxide formation when catalysts <b>1a</b> and <b>1c</b> are used.