J. K. Stille

Nucleophilic additions to platinum complexes

Complexes of the general formula ~--(diene)MX23, where M is platinum or palladium, react with alkoxides (i), ~-diketones (2), ethyl malonate (3,4), primary amines (5) and acetate ion (5) giving complexes containing metal-carbon ~-bonds. The stereochemical pattern of the oxyplatination and oxypalladation reactions with methanol has been determined (6,7). The overall reaction involves a methoxymetallation across one of the double bonds which has been made susceptible to the nucleophilic attack by methanol through coordination of the metal. We now have determined the stereochemistry of the addition of acetylacetone across the 5,6 double bond (norbornene double bond) of dichloro(endo-dicyclopentadiene)platinum (II) to be trans with the acetylacetone moiety exo. The new complex was prepared by allowing the anion of acetylacetone (formed from acetylacetone in the presence of sodium carbonate) to react with dichloro(endodicyclopentadiene)platinum (II). Prior preparation of the thallium salt is not necessary (8). Unlike the methoxymetallation, acetylacetone displaces the chloride ligands to give a complex whose stereochemistry is depicted in structure i. Hydrogenation