ISSN:
0021-8383
Schlagwort(e):
Chemistry
;
Organic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Photocatalytic Systems. XLVIII. Unusual Light-Induced Redox Reactions of Cobalt(III), Iron(III) and Copper(II) Complexes in Presence of Chromic Acid EstersThe coordination compounds[Co(NH3)5H2O]3+,[Co(NH3)4(H2O)2]3+,[Co(en)2(H2O)Cl]2+ (en = ethylendiamine), [L2(H2O)Fe-O-Fe(H2O)L2]4+ (L = 1,10-phenanthroline; 2,2′-bipyridine) and [CuL2]2+ (L = 2,9-dimethyl-1,10-phenanthroline) show no or neglegible photo redox reactions upon irradiation wave-length above 350 nm. However, in the presence of chromate(VI), water, and different alcohols like methanol, ethanol, i-propanol and n-propanol a very efficient light-induced formation of cobalt(II), iron(II) and copper(I) (φ = 0,7; Λirr = 375 nm) can be observed together with reduced generation of chromium(III). The participation of chromium(V) in the primary step of the photolysis of chromic acid esters was shown to be the reason for these unusual light-induced redox reactions. The coordination compounds under discussion behave as very efficient scavengers for chromium(V) connected with simultaneous reoxidation to chromate(VI) and reduction to the appropriate cobalt(II), iron(II) and copper(I) compounds. The general importance of the participation of chromium(V) in the primary step of the photolysis of chromate(VI) in non-aqueous solvents is also shown by investigations of the photochemical behaviour of the system metal complex/CrO4 - , Cr2O7 - /dimethylsulfoxide. Possible mechanisms of the light-induced reductions of the metal complexes are discussed.
Zusätzliches Material:
7 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/prac.19823240212
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