Adamson’s rule

In the case of mixed ligands photoreactivity may be predicted empiri- lly from considerations of the ligand field strencth (Adamson s rule), for O complex, the axis having the weakest average held as determined % the position of its respective ligands in the spectrochemical series will... 

There has been a great deal of work on the photoaquation of complexes of the general type Cr(A)5X, Cr(A)4(X)2, Cr(A)3(X)3 and their isomers, where A is an amine ligand. The reactions are often, but not always, antithermal, showing loss of the amine ligand. Information on these systems is summarized in the review by Kirk. The first attempt to e lain the variation in products and quantum yields was made by Adamson. This led to what are termed Adamson s rules, which are summarized as follows ... 

Some complexes that obey Adamson s rules are given by the first four examples in Table 7.6. 

Photochemistry.—Chromiumfm) continues to be one of the most popular metal ions for studies of photochemical reactions. Adamson s rules are widely applicable to photosubstitution reactions of chromium(m) for which there is theoretical support. " ... 

From observations of photoreactions of chromium(III) it has been generally found that the selectivity of the substitution pathways leading to the replacement of different ligands can be explained on the basis of two rules. These rules, which are commonly called Adamson s rules, can be expressed as follows ... 

Adamson s rules can be derived if the difference (/ -1) determines the ligand to be substituted. The photoactive state is determined by the average ligand field ax Ot ... 

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