Thumbnail
Access Restriction
Open

Author Hauenstein, B. L. (Jr.) ♦ Mandal, K. ♦ Demas, J. N. ♦ DeGraff, B. A.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY ♦ SOLAR ENERGY ♦ MERCURY CHLORIDES ♦ PHOTOLYSIS ♦ RUTHENIUM COMPLEXES ♦ OXIDATION ♦ BIPYRIDINES ♦ COMPARATIVE EVALUATIONS ♦ DATA ANALYSIS ♦ EXCITED STATES ♦ EXPERIMENTAL DATA ♦ LIGANDS ♦ LUMINESCENCE ♦ PHENANTHROLINES ♦ PHOTOSENSITIVITY ♦ RADICALS ♦ REDOX POTENTIAL ♦ SPECTROSCOPY ♦ AROMATICS ♦ AZAARENES ♦ AZINES ♦ CHEMICAL REACTIONS ♦ CHLORIDES ♦ CHLORINE COMPOUNDS ♦ COMPLEXES ♦ DATA ♦ DECOMPOSITION ♦ ENERGY LEVELS ♦ HALIDES ♦ HALOGEN COMPOUNDS ♦ HETEROCYCLIC COMPOUNDS ♦ INFORMATION ♦ MERCURY COMPOUNDS ♦ MERCURY HALIDES ♦ NUMERICAL DATA ♦ ORGANIC COMPOUNDS ♦ ORGANIC NITROGEN COMPOUNDS ♦ PHOTOCHEMICAL REACTIONS ♦ PYRIDINES ♦ SENSITIVITY ♦ TRANSITION ELEMENT COMPLEXES ♦ Photochemistry ♦ Chemical & Physicochemical Properties ♦ Solar Energy Conversion- Photochemical, Photobiological, & Thermochemical Conversion- (1980-) ♦ Organic Chemistry- Chemical & Physicochemical Properties- (-1987)
Abstract Excited-state interactions of tris(..cap alpha..-diimine)ruthenium(II) photosensitizers with HgCl/sub x//sup 2-x/(x = 2,3,4) were studied in aqueous media with use of luminescence quenching and flash photolysis methods. HgCl/sub 2/, HgCl/sub 3//sup -/, and HgCl/sub 4//sup 2-/ exhibit sufficiently different quenching constants to permit luminescence determination of the equilibrium constants for their formation. Quenching proceeds via oxidative electron transfer to yield Ru(III) and a HgCl/sub x/sup 1-x/ free radical. The quenching data are interpreted with use of Marcus electron-transfer theory. The experimental order of reactivity (HgCl/sub 4//sup 2-/<<HgCl/sub 2/ <HgCl/sup 2//sup -/) differs from that expected on purely electrostatic grounds. The low reactivity of HgCl/sub 4//sup 2-/ arises from a larger inherent barrier to electron transfer (..delta..G/sup ++/(0). From the quenching data the redox potentials for the otherwise unmeasureable Hg(II) + e/sup -/ ..-->.. Hg(I). Reactions are determined to be approx. -0.80 V vs NHE. Back electron transfer between Ru(III) and Hg(I) in the encounter pair proceeds very rapidly, precluding detection of the Hg(I) free radicals. The 2,2'-bipyridine and 1,10-phenanthroline derivative appear to behave differently, and this may cloud the interpretation of photochemical and photophysical studies that mix the two types of complexes.
Educational Use Research
Learning Resource Type Article
Publisher Date 1984-04-11
Publisher Place United States
Journal Inorg. Chem.
Volume Number 236
Issue Number 8
Organization Univ. of Virginia, Charlottesville


Open content in new tab

   Open content in new tab