Isolation of alkyl- and acyl-palladium complexes containing rigid bidentate nitrogen ligands by stepwise successive insertion of CO and alkenes

Fast successive stoichiometric insertions of carbon monoxide and norbornadiene (R′CHCHR″) have been observed into Pd–C bonds of neutral [Pd(Me)Cl(An-bian)] leading to thermally stable multiinsertion products of the type Pd–C(O)–CH(R′)–CH(R″)–C(O)-Me 4 and Pd–CH(R′)–CH(R″)–C(O)–CH(R′)–CH(R″)–C(O)–Me5, the stability of which is due to the rigidity of the bidentate nitrogen ligands employed; these are the first isolated and fully characterized compounds which are models for intermediates in the copolymerization of carbon monoxide and alkenes.