The role of chelate-forming ligands in the generation of the catalytic function of Cu{sup 2+} complexes based on hydrozone imines in liquid-phase oxidation of cyclohexene by molecular oxygen

Journal Article · Thu Sep 01 04:00:00 EDT 1994 · Kinetics and Catalysis

OSTI ID:39368

Zakharov, A N; Panova, G V; Zefirov, N S ^[1]

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1. Moscow State Univ. (Russian Federation)

The dependence of the catalytic activity of bicyclic and tricyclic Cu{sup 2+} chelates based on hydrazone imines in a model reaction of liquid-phase oxidation of cyclohexene by molecular oxygen on the donor-acceptor properties of ligands and the number of coordinating atoms of the ligands is studied. Decreasing this number with the retention of the coordination geometry of the chelate center results in the enhancement of the catalytic activity of the Cu{sup 2+} chelate owing to an increase in its stereochemical lability. Introduction of different substituents (C{sub 6}H{sub 5}CO, CH{sub 3}CO, and CF{sub 3}CO) at the {gamma}-position of quasi-aromatic metallocycles results in a decrease in the effective rate constants for cyclohexene oxidation in the series C{sub 6}H{sub 5}CO > CH{sub 3}CO > CF{sub 3}CO. Cu{sup 2+} complexes with a tetragonal distortion based on hydrazone imines have unstable structures and isomerize into square-planar chelates during the catalytic oxidation of cyclohexene. {open_quotes}Flattening{close_quotes} of the chelate center results in a decrease in the rate of the catalytic reaction, since the tetrahedrally distorted Cu{sup 2+} complexes are more active than their square-planar isomers. Kinetics of cyclohexene oxidation by molecular oxygen in the presence of stereochemically unstable Cu{sup 2+} chelates is studied, and effective rate constants for oxidation and relaxation times are calculated. The catalytic activity and relaxation times correlate with the {open_quotes}energy gap{close_quotes} of Cu{sup 2+} chelates.

• OSTI ID: 39368
• Journal Information: Kinetics and Catalysis, Journal Name: Kinetics and Catalysis Journal Issue: 5 Vol. 35; ISSN 0023-1584; ISSN KICAA8
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
AROMATICS
CATALYTIC EFFECTS
COPPER COMPLEXES
CYCLOALKENES
IMINES
OXIDATION