Chromium photochemistry

Chromium, bis(l,2-ethanediamine)difluoro-photochemistry, 1,393 Chromium, bis(l, 2-ethanediamine)oxalato-coordination isomerism, 1, 183 Chromium, diamminetetrakis(isothiocyanato)-photoaquation chemical actinometer. 1,409 photochemistry reactivity, 1, 398... 

Chromium, hexacyano-, 3, 703, 777 hexaamminecobaltate coordination isomerism, 1, 183 ligand field photochemistry, 1, 398 photochemistry excited states, 1, 398 production, 3, 704 Chromium, hexafluoro-, 3, 927 Chromium, hexabalo-, 3, 889 Chromium, hexaiodo-, 3, 766 Chromium, hexakis(dimethyl sulfoxide)-photoanation, 1, 399 Chromium, u-oxalatodi-reduction... 

Chromium, tris( 1,2-ethanediamine)-pentacyanonickelate isomers, 1, 207 photochemistry reactivity, 1, 398 photolysis, 1. 397 reactions, 1, 27 trichloride... 

For a review on chromium carbene complex photochemistry in organic syntheses see Hegedus LS (1997) Tetrahedron 53 4105... 

The high-pressure photochemistry technique also contributed to clarifying the mechanism of the chromium carbonyl catalyzed water gas shift reaction (Equation 37) /38/. 

It will become evident from this discussion of cobalt(III) and chromium(III) photochemistry that a fortunate combination of many factors makes these systems especially amenable to mechanistic investigation this is not the case for most other inorganic systems. For this reason, the progress made toward understanding the photochemical reactions of cobalt(III) and chromium(III) complexes may not be easily duplicated in other areas and it is useful to inquire whether conclusions reached here can be generalized. It is my belief that they can, and this and the next section are intended to place the subsequent discussion in the perspective of inorganic photochemistry. 

Two rather different points of view have been maintained concerning the general question of mechanisms in inorganic photochemistry. This section defines both of these and attempts to indicate the evidence in favor of each subsequent sections will consider in detail the applicability of various mechanistic proposals to the study of the photochemistry of cobalt(III) and chromium(III). 

H. PHOTOCHEMISTRY OF CHROMIUM(HI) COMPLEXES A. Survey of Thermal and Photochemistry of Chromium(III) Complexes... 

Much less is known about photoinitiated ligand exchange reactions of coordination complexes of cobalt(III) and other de ions than is the case for chromium(III). With the exception of the cobalt(III) ammines, however, available data suggest that photochemical ligand exchange reactions of cobalt(III) and d6 systems involve the thermally equilibrated 17 g and/or 37, states of the complex as intermediates. The reasoning is completely analogous to that described earlier with respect to chromium(III) photochemistry. 

Robert Plane I would like to comment on the photochemistry of these complexes, particularly the chromium which I think are well chosen for at least two of Dr. Gray s reasons. First, in the case of chromium, unlike cobalt, the charge transfer band is well separated, so that one can study the d-d transitions, at least in certain systems where one has six ligands all alike, and there is no Jahn-Teller splitting, and one has a fairly good idea as to the assignment of bands. 

Table 2 Photochemistry of Mixed-ligand Chromium(III) Complexes upon Irradiation into the Lowest Quartet Ligand...

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