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 04:00:00 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), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 98:22; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

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