Formalisms for Electron Exchange Kinetics in Aqueous Solution, and the Role of Ab Initio Techniques in Their Implementation

Conference · Tue Jan 01 00:00:00 EST 1980 · International Journal of Quantum Chemistry, Supplement: Proceedings of the International Symposium on Atomic, Molecular, and Solid-StateTheory, Collision Phenomena, Quantum Statistics, and Computational Methods

DOI:https://doi.org/10.1002/qua.560180839· OSTI ID:5429003

Newton, M. D.

Formalisms suitable for calculating the rate of electron exchange between transition metal complexes in aqueous solution are reviewed and implemented in conjunction with ab initio quantum chemical calculations which provide crucial off-diagonal Hamiltonian matrix elements as well as other relevant electronic structural data. Rate constants and activation parameters are calculated for the hex-aquo Fe^{2 +}-Fe³⁺ system, using a simple activated complex theory, a non-adiabatic semi-classical model which includes nuclear tunnelling, and a more detailed quantum mechanical method based on the Golden Rule. Comparisons are made between calculated results and those obtained by extrapolating experimental data to zero ionic strength. All methods yield similar values for the overall rate constant (∾ 0.1 L/(mol-sec)). The experimental activation parameters (δH^‡ and δS^‡) are in somewhat better agreement with the semi classical and quantum mechanical results than with those from the simple activated complex theory, thereby providing some indication that non-adiabaticity and nuclear tunnelling may be important in the Fe^2+/3+ exchange reaction. It is concluded that a model based on direct metal-metal overlap can account for the observed reaction kinetics provided the reactants are allowed to approach well within the traditional contact distance of 6.9 Å. 6 figures, 7 tables.

• Research Organization: Brookhaven National Lab. (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: EY-76-C-02-0016; DE-AC02-76CH00016
• OSTI ID: 5429003
• Report Number(s): BNL-27677; CONF-800369-1
• Journal Information: International Journal of Quantum Chemistry, Supplement: Proceedings of the International Symposium on Atomic, Molecular, and Solid-StateTheory, Collision Phenomena, Quantum Statistics, and Computational Methods, Vol. 18, Issue S14; Conference: International Symposium on Atomic, Molecular, and Solid-State Theory, Flagler Beach, FL, USA, 10-14 Mar 1980
• Publisher: John Wiley & Sons, Inc.
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
IRON COMPLEXES
ELECTRON EXCHANGE
AQUEOUS SOLUTIONS
CHEMICAL REACTION KINETICS
TRANSITION ELEMENT COMPLEXES
COMPLEXES
DISPERSIONS
ELECTRON TRANSFER
KINETICS
MIXTURES
REACTION KINETICS
SOLUTIONS
400201* - Chemical & Physicochemical Properties