Photochemistry of complex ions. XIII. The cis-dichlorobis(ethylenediamine)cobalt(III) and cis-chloroaquobis(ethylenediamine)cobalt(III) complexes

Abstract

irradiation of the first or second ligand field (Li and L2) bands caused ligand aquation, although at a low level of absolute quantum yield. Due to the choice of the nonammine ligands, and the irradiation wavelength (no charge-transfer absorption), complications due to photoinduced redox decomposition were minimal, and the photochemistry could be interpreted in terms of the photolysis rules used for Cr(III) complexes.2 (2) A. W. Adamson, J. Phys. Chem., 71, 798 (1967).

Stereochemical consequences of the ligand field photolyses of dihalo- and aquohalotetraamminerhodium(III) complexes in aqueous solution

“…Similarly, excited-state electron-transfer reactions to Fe3+ 6 and energy-transfer studies to Cr(III) complexes seemed to indicate that ' for [Ru(phen)3]2+ (phen = 1,10-phenanthroline) might be 0.5-0.6 times as large as that of [Ru(bpy)3]2+. 13 Although the flash-photolytic work has probably been shown to be in error because of an incorrect assumption concerning the *[Ru(bpy)3]2+ excited-state absorption,5,9,13 there still seem to be conflicting claims and uncertainties concerning the correctness of ' for Ru(II) and Os(II) sensitizers.…”

Photochemistry of coordination compounds. 15. trans- and cis-Chloro(ammine)bis(ethylenediamine)cobalt dinitrate

“…The triangular graphical procedure involved is that previously described. 5 Briefly stated, if a species A photolyzes (or, in general, reacts) to give products B and C, it follows that for any mixture the apparent extinction coefficient (optical density/path length times total concentration)…”

“…One product, inz/ts-Co(en)2(H20)Cl2+ is known to be photoinert. 5 The other, rrans-Co(en)2(NH3)(H20)3+, probably has a very low quantum yield for ammonia aquation, the preferred process. Thus the yield for ammonia aquation of Co(NH3)5(H20)3+is only 1.8 X 10-4,4 and would be even less for the trans aquoammine if the general pattern of lower yields for Co(en)2(NH3)Cl2+ vs. Co(NH3)5C12+ species is followed.…”

Photochemistry of macrocyclic coordination compounds. I. Cobalt(III) containing a tetradentate equatorial ligand, PnAO [2,2'-(1,3-diaminopropane)bis(2-methyl-3-butanone)oxime]

“…The use of a laser-microcell technique has recently made it possible to measure low quantum yields even with complexes whose dark reaction times are of the order of minutes, and it is now evident that irradiation of the Li or L2 bands of cobalt(III) ammines and acidoammines leads to stereospecific substitutional types of processes which can be accounted for by heterolytic bond fission according to rules developed for the analogous Cr(III) complexes. [3][4][5][6] The low quantum yields (relative to Cr(III) complexes) were tentatively attributed to more rapid radiationless deactivation rather than to smaller reactivity of the thermally equilibrated excited (thexi3) state. The term thexi was coined in response to the felt need to distinguish between thermally equilibrated excited states and Franck-Condon states.…”