Quenching of the doublet excited state of tris(polypyridine)chromium(II) ions by oxalate ions: An example of irreversible electron transfer

Journal Article · Wed Jul 26 00:00:00 EDT 1989 · Inorganic Chemistry; (USA)

DOI:https://doi.org/10.1021/ic00314a023· OSTI ID:6985670

Steffan, C R; Bakac, A; Espenson, J H ^[1]

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1. Iowa State Univ., Ames (USA)

The kinetics and mechanism of the reductive quenching of {sup 2}E CrL{sub 3}{sup 3+} (L = 2,2{prime}-bipyridine, 1,10-phenanthroline, and their substituted analogues) by oxalate were studied. Quenching rate constants vary from 85.4 {times} 10{sup 5} M{sup {minus}1} s{sup {minus}1} for the 5-chloro-1,10-phenanthroline complex to 0.21 {times} 10{sup 5}M{sup {minus}1} s{sup {minus}1} for the 4,4{prime}-dimethyl-2,2{prime}-bipyridine complex and depend on the E{sup 0}{sub 3*/2} value. The mechanism involves an ion-pairing preequilibrium followed by rate-limiting electron transfer. The CO{sub 2}{sup {sm bullet}{minus}} produced in the quenching step reacts with ground state CrL{sub 3}{sup 3+} to produce another mole of CrL{sub 3}{sup 2+} in the case of the 2,2{prime}-bipyridine complex and its substituted analogues, while in the case of the 1,10-phenanthroline complex and its analogues a secondary transient is produced that decays to CrL{sub 3}{sup 2+}. 27 refs., 4 figs., 1 tab.

• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6985670
• Journal Information: Inorganic Chemistry; (USA), Journal Name: Inorganic Chemistry; (USA) Vol. 28:15; ISSN 0020-1669; ISSN INOCA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
AROMATICS
AZAARENES
AZINES
BIPYRIDINES
CARBOXYLIC ACID SALTS
CHROMIUM COMPLEXES
COMPLEXES
DATA
ELECTRON TRANSFER
ENERGY LEVELS
EXCITED STATES
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
INFORMATION
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXALATES
PHENANTHROLINES
PYRIDINES
QUENCHING
TRANSITION ELEMENT COMPLEXES