Reactions of dioxygen complexes. Oxidative dehydrogenation of 1,6-bis(2-pyridyl)-2,5-diazahexane through cobalt dioxygen complex formation

Journal Article · Wed Jun 01 00:00:00 EDT 1988 · Inorg. Chem.; (United States)

DOI:https://doi.org/10.1021/ic00284a024· OSTI ID:5637455

Basak, A K; Martell, A E

The formation constants and oxygenation constants of the cobalt(II) complexes of 1,6-bis(2-pyridyl)-2,5-diazahexane (PYEN) have been determined by potentiometric equilibrium measurements under nitrogen and oxygen. The kinetics of the oxidative degradation of the coordinated ligand in the cobalt dioxygen complex have been measured spectrophotometrically, and the rate constants of two parallel degradation reactions have been determined. Both reactions were found to be second order, first order with respect to the concentration of the dioxygen complex and first order with respect to the hydroxide ion concentration. Kinetics and product analysis reveal that one of the terminal aminomethyl residues of the ligand PYEN undergoes two-electron oxidation to form the corresponding imine, which under the reaction conditions employed is converted to pyridine-2-carboxyaldehyde, identified semiquantitatively as the (2,6-dinitrophenyl)hydrazone. Comparisons of these results with those of systems investigated previously, and the large kinetic deuterium isotope effect for the dehydrogenation reaction, are employed as the basis of a proposed reaction mechanism, which involves deprotonation of an aliphatic amino group in a preequilibrium step. Reaction mechanisms are suggested. 30 references, 10 figures, 3 tables.

• Research Organization: Texas A and M Univ., College Station (USA)
• OSTI ID: 5637455
• Journal Information: Inorg. Chem.; (United States), Vol. 27:11
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
COBALT COMPLEXES
CHEMICAL REACTIONS
HETEROCYCLIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOMETALLIC COMPOUNDS
OXYGEN
EXPERIMENTAL DATA
REACTION KINETICS
COMPLEXES
DATA
ELEMENTS
INFORMATION
KINETICS
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties
400202 - Isotope Effects
Isotope Exchange
& Isotope Separation