Photoinitiated two-electron oxidation of Tris(1,10-phenanthroline)vanadium(II)

Journal Article · Wed May 20 00:00:00 EDT 1987 · Inorg. Chem.; (United States)

DOI:https://doi.org/10.1021/ic00257a019· OSTI ID:6800296

Shah, S S; Maverick, A W

The redox and photochemical properties of vanadium polypyridine complexes have been combined to achieve the first example of photoredox-initiated two-electron oxidation at a single transition-metal center. Cyclic voltammetry of V(phen)/sub 3//sup 2 +/ (phen = 1,10-phenanthroline) in CH/sub 2/Cl/sub 2/ shows three reversible redox couples due to V(phen)/sub 3//sup 3+/2+/, V(phen)/sub 3//sup +/0/, with half-wave potentials of 0.09, -1.51, and -1.70 V, respectively, vs. Fc/Fc/sup +/ (Fc = ferrocene). Solutions of the vanadium(III) complex ((phen)/sub 2/ V(..mu..-OH)/sub 2/V(phen)/sub 2/)/sup 4 +/ in CH/sub 3/CN exhibit a single irreversible oxidation wave, which is probably associated with formation of a mononuclear vanadium(IV) complex. This electrogenerated vanadium(IV) species is also electroactive, showing quasi-reversible oxidation and reduction waves. Similar quasi-reversible waves observed in the V(phen)/sub 3//sup 2 +/ voltammograms are attributable to the same species, formed by hydrolysis of V(phen)/sub 3//sup 3 +/ and subsequent rapid oxidation. In buffered aqueous solutions (pH greater than or equal to 8), ((phen)/sub 2/ V(..mu..-OH)/sub 2/ V(phen)/sub 2/)/sup 4 +/ spontaneously reduces the electron acceptors MV/sup 2 +/ (methylviologen or 1,1'-dimethyl-4,4'-bipyridinium) and Fe(CN)/sub 6//sup 3 -/. The vanadium-containing electron-transfer product is a VO/sup 2 +/ complex, as identified by its ESR spectrum. Thus, irradiation of a solution (pH 8) of V(phen)/sub 3//sup 2 +/ and MV/sup 2 +/ and MV/sup 2 +/ (lambda > 500 nm) leads to the one-electron photooxidation of V(phen)/sub 3//sup 2 +/, followed by thermal electron transfer to produce VO/sup 2 +/.

• Research Organization: Washington Univ., St. Louis, MO
• OSTI ID: 6800296
• Journal Information: Inorg. Chem.; (United States), Journal Name: Inorg. Chem.; (United States) Vol. 26:10; ISSN INOCA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
AQUEOUS SOLUTIONS
AROMATICS
AZAARENES
CHEMICAL REACTIONS
CHEMISTRY
COMPLEXES
DATA
DISPERSIONS
ELECTRON SPIN RESONANCE
ELECTRON TRANSFER
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
INFORMATION
MAGNETIC RESONANCE
MIXTURES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDATION
PH VALUE
PHENANTHROLINES
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
RESONANCE
SOLUTIONS
TRANSITION ELEMENT COMPLEXES
VANADIUM COMPLEXES
VOLTAMETRY