Photochemical Studies of Hydroxo-Bridged Complexes of Chromium (III)

Author

Ronald Raymond Ruminski

Publication Date

12-7-1977

Abstract

The acid solution and solid state photolysis in both visible and ultraviolet regions of the spectrum for µ-hydro­xo-bis[pentaamminechromium(III)] chloride, and the solution photolysis in the visible and 1 traviolet region of the spectrum for µ-hydroxo-bis[pentaarnrninechr rnium(III)] perchlorate, have been studied. The ultraviolet irradiation of µ-hydroxo-bis[pentaamminechromium(III)] chloride in HCl and CHlO₄ produces a redox photoproduct identified as HCrO₄^-, although the rate of production of HCrO₄^- in HClO₄ is slower than in HCl. Photochemical cleavage of the hydroxo-bridge occurs in the ultraviolet photolysis of µ -hydroxo-bis[pentaanuninechromium(III)] chloride and is 1.9 times faster than the corresponding thermal reaction. In addition to the redox and bridge-cleavage reactions photosubstitution products including aquoerythrochromium (III) are also observed. The ultraviolet photolysis of µ -hydroxo-bis [pentaamminechromi um (III)] perchlorate in HClO₄ produces no redox product and the photochemical hydroxo-bridge cleavage occurs at a rate of 1.6 times faster than via thermal reaction. The photosubstitution products observed in HClO₄ irradiations of µ -hydroxo-bis [pentaamminechromium(III)] chloride in HCl. Visible photolysis of the L₁ bands (502 nm) produce neither redox nor photochemically accelerated hydroxo­bridge cleavage. The photosubstitution products of the visible irradiations are solvent dependent, with aquo­erythrochromium(III) being a photosubstitution product in both solvents. The photosubstitution products are identical to the photosubstitution products of the ultra­violet irradiations. High intensity Xenon excitation of solid µ-hydroxo- bis[pentaamminechromium(III)] chloride produces Cr₂O₃, while low intensity photolysis produce NH₄Cl and photosubstitution products including aquoerythrochromium(III).

Language

English

Document Type

Thesis

Degree Name

Chemistry

Level of Degree

Masters

Department Name

Department of Chemistry and Chemical Biology

First Committee Member (Chair)

William Fletcher Coleman

Second Committee Member

Robert Edwin Tapscott

Third Committee Member

Fritz Schreyer Allen

Recommended Citation

Ruminski, Ronald Raymond. "Photochemical Studies of Hydroxo-Bridged Complexes of Chromium (III)." (1977). https://digitalrepository.unm.edu/chem_etds/209