Insertion of Carbon Monoxide and Alkenes in Palladium-Carbon Bonds of Complexes Containing Rigid Bidentate Nitrogen Ligands: The First Example of Isolated Complexes in Stepwise Successive Insertion Reactions on the Way to Polyketones’

Facile successive insertion of carbon monoxide and strained alkenes has been observed for both neutral Pd(R)X(Ar-BIAN) and cationic [Pd(R)(MeCN)(Ar-BIAN)]SO 3 CF 3 complexes, i.e., complexes containing the rigid bidentate nitrogen ligands bis(arylimino)acenaphthene (Ar-BIAN; Ar=p-MeOC 6 H 4 (p-An), p-MeC 6 H 4 (p-Tol), o,o'-i-Pr 2 C 6 H 3 ), leading to the formation of new multiple insertion products of the type Pd{CH(R'CH(R')C(O)CH(R')CH(R')C(O0)R}X(Ar-BIAN). It appears that the rigidly chelating Ar-BIAN ligands have an activating effect on the insertion of CO and alkenes in palladium-carbon bonds as compared to other (bidentate) phosphorus and nitrogen ligands and a stabilizing effect on the Pd-acyl and Pd-alkyl complexes formed