Reductive quenching of /sup 2/E Cr(bpy)/sub 3//sup 3+/ by Fe/sup 2+/ and Cr(bpy)/sub 3//sup 2+/
The reductive quenching of the doublet excited state of Cr(bpy)/sub 3//sup 3+/ by Fe(H/sub 2/O)/sub 6//sup 2+/ at pH 1 in aqueous perchlorate solutions produces Cr(bpy)/sub 3//sup 2+/; k = (5.3 /plus minus/ 0.3) /times/ 10/sup 6/ M/sup /minus/1/ s/sup /minus/1/ at 25/degree/C and 1 M ionic strength. Concurrent reduction of /sup 2/E Cr(bpy)/sub 3//sup 3+/ by Cr(bpy)/sub 3//sup 2+/, unrecognized in previous studies, provides a catalytic route for the deactivation of the excited state. This reaction can be eliminated by the addition of Fe(H/sub 2/O)/sub 6//sup 3+/, which rapidly oxidizes the chromium(II) complex; k = 9.2 /times/ 10/sup 8/ M/sup /minus/1/ s/sup /minus/1/. The quenching of /sup 2/E Cr(bpy)/sub 3//sup 3+/ by Cr(bpy)/sub 3//sup 2+/ was demonstrated by the effect of Fe/sup 2+ on the excited state lifetimes and yields of Cr(bpy)3//sup 2+/ in experiments with Fe/sup 2+/ as quencher. This required solution of the differential rate equations by numerical integration; the program KINSIM was used and gave the value k/sub Cr/ = (5 /plus minus/ 3) /times/ 10/sup 9/ M/sup /minus/1/ s/sup /minus/1/. The indicated quenching reaction was also observed directly. 31 refs., 2 figs., 1 table.
- Research Organization:
- Iowa State Univ., Ames (USA)
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 5833281
- Journal Information:
- Inorg. Chem.; (United States), Journal Name: Inorg. Chem.; (United States) Vol. 27:2; ISSN INOCA
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
AZINES
BIPYRIDINES
CHEMICAL REACTIONS
CHROMIUM COMPLEXES
COMPLEXES
DATA
ENERGY LEVELS
EXCITED STATES
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
INFORMATION
IRON COMPLEXES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PYRIDINES
QUENCHING
TRANSITION ELEMENT COMPLEXES
WATER