Abstract: | Abstract Theoretical studies were carried out on a series of bis(phosphine) palladium ketene complexes (PR3)2Pd(CH2=C=O), and on the related CH2=C=O and Pd(PR3)2 molecular fragments in order to investigate the electronic structure and the bonding of the ketene ligand to the metal fragment in these complexes. An analysis of the frontier MOs has been performed in order to understand the interactions between the ketene and the metal fragments. The calculated results have shown that the η2-(C,C) mode is preferred over the η2-(C,O) mode by 10–15 kcal/mol in bis(phosphine) palladium ketene complexes. The basicity and bulkiness of the phosphine ligands PR3 have little effect on the bonding mode in (PR3)2Pd(CH2=C=O) complexes. The most stable structure was calculated to be the η2-(C,C) square planar geometry with the CH2 group of ketene out of the molecular plane. Comparison and discussion between the two bonding modes were also presented in this paper. |