PI-ALLYL-PALLADIUM COMPLEXES STABILIZED B Y TRIPODAL OXYGEN LIGANDS [(C5H5)CO(P(OME)(2)O)(3)](-) .2. ELIMINATION INSTEAD OF C-C COUPLING INREACTION WITH RESONANCE-STABILIZED CARBANIONS

The reaction of the complexes [L(OMe)Pd(propenyl)] (1) and [L(OMe)Pd(2 -methyl-propenyl)] (2) (L(OMe)(-)=[(C5H5)Co{P(OMe)(2)O}(3)](-)) with s odium malonate results in the formation of the anticipated C-C couplin g products (2-R-C3H5)CH(CO(2)Et)(2) while [L(OMe)Pd{4-6-eta-(3-oxo-cho lestenyl))] (4) and [L(OMe)Pd(4-6-eta-(cholestenyl)}] (5) react with e liminination to give the corresponding cholestadienes. With sodium 2-a cetylcyclopentanoate (Na acp), ligand substitution takes place in the reaction with 1-3 (3=[L(OMe)Pd(2-(t)butyl-propenyl)]) to give complexe s of the type [(2-R-propenyl)Pd(acp)]. Their stability depends on the substituent of the allyl group. While [(propenyl)Pd(acp)] decomposes a t room temperature, [(2-(t)butyl-propenyl)Pd(acp)] and [(2-methyl-prop enyl)Pd(acp)] are air stable compounds which could be isolated.