Photosubstitution reactions stereomobility

The systematization of the experimental data has been extended so as to include also the stereochemistry of the reactions(9). In 1978, we suggested(lO) the validity of Table I. At the time, this Table seemed to accomodate nearly all the available experimental facts - that was approximately 35 different photosubstitution reactions, both of d - and d -systems. For instance, in the case of axial labilization, a trans-complex of Cr generally gives rise to a cis-product upon photosubstitution (stereomobility) while a trans-complex of Co yields a trans-product (stereoretention),... 

L is the leaving ligand in the latter case, Y is the leaving ligand. But the same penta-coordinated structure is supposed to be the reaction intermediate since the photosubstitution is characterized by a clearly pronounced stereomobility, S comes in cis from X. 

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