Correlated ab initio calculations have been performed on three dipalladium(I) complexes. These compounds differ both by the metal–metal interaction and by the metal–ligand interaction. The [Pd2Cl2(μ −H2PCH2PH2)2] complex exhibits a σ overlap between the two binding metallic orbitals and has no bridging ligand. In [Pd2Cl4(μ −CO)2]2−, the leading interaction between the two palladium involves a π overlap between the metallic orbitals and goes through the two bridging CO ligands. In [Pd2Cl2(μ −CO)(μ −H2PCH2 PH2)2], a single CO ligand bridges the two palladium atoms which interact through a hybrid σ–δ overlap. The three compounds also differ by the metal–metal distances. Surprisingly enough, while the palladium atoms are formally d 9 in all these complexes, none of them is paramagnetic. We propose here a detailed analysis of the electronic structures of these compounds and rationalize their chemical structures as well as the role of back-donation in the CO bridged compounds. Finally, since highly correlated treatments are used to describe these complexes, a detailed study of the role of both non-dynamical and dynamical correlations is performed. Concerning the [Pd2Cl4(μ −CO)2]2− complex, this analysis has revealed that the complex is not bound at the lowest correlated levels of calculation and therefore dynamical correlation is alone responsible for its binding energy.