Theoretical Study of the Metal–Metal Interaction in Dipalladium(I) Complexes |
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Authors: | Tahra Ayed Nathalie Guihéry Bahoueddine Tangour Jean-Claude Barthelat |
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Institution: | (1) Laboratoire de Physique Quantique, IRSAMC/UMR5626, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 4, France;(2) Unité de Recherche de Chimie Théorique et Réactivité, Institut Préparatoire aux Etudes d’Ingénieur d’El Manar, Université de Tunis-El Manar, Tunis, Tunisia |
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Abstract: | 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. |
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Keywords: | Dipalladium(I) complexes Metal– metal interaction CASSCF method DFT method |
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