Ligand substitution reactions nonsymmetrical

Nonsymmetrical ligand substitution reactions also play an important role in a number of biological processes. One of these concerns the antitumor activity of platinum metal complexes, for which substitution processes involving DNA moieties are generally accepted to... 

This means that the coordination sphere of the reactants remains intact in the former case and is modified by ligand substitution in the latter which will naturally affect the associated volume changes. In our earlier work we mainly concentrated on the analysis of nonsymmetrical electron transfer reactions (8), that is, reactions in which redox products are formed and for which the overall driving force and reaction volume will not be zero. Some typical examples of such studies will be discussed in more detail to form a basis for the next section, which deals with long distance electron transfer processes. 

One methyl group in the dimethyl derivatives 406a (R = R7 = Me) may be also cleaved by the reaction with f-BuPO(OH)2240. According to the X-ray data, the t-butylphosphonic acid ligand in the resulting nonsymmetrically substituted stannocane [r-BuP(Oj(OI I)0 MeSn(CH2CH2( l 12)2 NMe 408 coordinates with the tin center only via the oxygen atom. 

Under specific conditions, the synthesis of nonsymmetrical COTTs can be achieved through a cross-reaction with two different diynes. The synthesis of highly substituted COTTs [64] and utilization of the symmetrical dinaphthocyclooctate-traene as ligand of rhodium were reported by the same group [65]. 

---