STEREOCHEMICAL EFFECTS ON THE CATALYTIC PROPERTIES OF TRICYCLIC CU(II) COMPLEXES WITH BIS(OXA, AZA) CHELATE LIGANDS

Catalytic properties of Cu(II) tricyclic chelates of tetradentate Schi ff bases from salicylaldehyde or enaminoketones from benzoylacetone an d 1,2-ethylenediamine or 1,4-tetramethylenediamine were studied in cyc lohexene liquid-phase oxidation by molecular oxygen. The initial catal ytic activity of Cu(II) chelates of pseudotetrahedral structure based on 1,4-tetramethylenediamine is higher than the catalytic activity of square-planar Cu(II) complexes that are 1,2-ethylenediamine derivative s. The rate of the catalytic oxidation of cyclohexene in the presence of square-planar Cu(II) chelates is constant, whereas the catalytic ac tivity of the pseudotetrahedral chelate, a derivative of salicylaldehy de, monotonically decreases and attains the steady-state value, which is different from that for the 1,2-ethylenediamine-based Cu(II) comple x. The non-steady-state behavior of the pseudotetrahedral Cu(II) chela tes is stipulated by rotational isomerization that yields a stable fla ttened isomer of lower catalytic activity.