Reactions of octahedral complexes: the stereochemical consequences

1. Reactions of octahedral complexes: the stereochemical consequences

2. Stereochemistry of a dissociation reaction at an Oh complex

3. X is cis to A, and A is a  donor vacant metal d2sp3 orbital  donation stabilises the square pyramidal intermediate Hence get retention of stereochemistry – close to 100% cis The nature of A will control the nature of the intermediate, and hence the stereochemistry of the products

4. trans product Y Y viewed down the z axis  donation stabilises the trigonal bipyramidal intermediate Y • X is trans to A, and A is a  donor Leads to a mixture of cis and trans

5. The better the  donor ability of A, the more the trigonal bipyramidal structure is formed, and the more of the cis product will be produced.

6. Racemisation of tris-chelate complexes Three pathways Bailar twist

9. Ray-Dutt twist

12.   Dissociation/Reformation