Direct measurement of spin-state lifetimes in solution for some iron(II) spin equilibrium complexes derived from hexadentate ligands. [Methanol and aqueous solutions]

Journal Article · Wed Oct 27 00:00:00 EDT 1976 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00438a036· OSTI ID:7332482

Hoselton, M A ^[1]; Drago, R S; Wilson, L J; Sutin, N

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1. Univ. of Illinois, Urbana

The rates of intersystem crossing of the iron(II) spin equilibrium systems (Fe(6-MePy)(Py)/sub 2/tren)(PF/sub 6/)/sub 2/ and (Fe(6-MePy)/sub 2/(py)tren)(PF/sub 6/)/sub 2/ have been measured by the laser Raman temperature-jump method. Absorbance changes at the charge-transfer band maximum (lambda/sub max/ approximately equals 560 nm) following the temperature-jump perturbation show that the approach to equilibrium occurs by a first-order process. The rate constant for the forward (k/sub 1/) and reverse (k/sub -1/) steps in the FeL/sup 2 +/ (low spin) reversible FeL/sup 2 +/ (high spin) reaction in methanol or aqueous solutions are: L = (6-MePy)(Py)/sub 2/tren, k/sub 1/ = 4 x 10/sup 5/, k/sub -1/ = 8 x 10/sup 6/ s/sup -1/; L = (6-MePy)/sub 2/(Py)tren, k/sub 1/ = 4 x 10/sup 6/, k/sub -1/ = 5 x 10/sup 6/ s/sup -1/ at 25/sup 0/C. The kinetics are discussed and it is shown that the results are consistent with the suggestion that a spin-state equilibrium could precede electron transfer in reductions of the hexaaquocobalt(III) ion.

• OSTI ID: 7332482
• Journal Information: J. Am. Chem. Soc.; (United States), Vol. 98:22
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
IRON COMPLEXES
CHEMICAL REACTION KINETICS
HIGH SPIN STATES
METHANOL
SOLVENT PROPERTIES
WATER
ALCOHOLS
COMPLEXES
ENERGY LEVELS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
KINETICS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
REACTION KINETICS
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties