Collect. Czech. Chem. Commun. 2007, 72, 703-714

Remote Metal-Arene π Bonding in Organometallic Complexes: a DFT Study

Paulo J. Costaa, Maria José Calhordaa,* and Paul S. Pregosinb

a Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
b Laboratorium für Anorganische Chemie, ETHZ, Hönggerberg, 8093 Zürich, Switzerland


The observation that the 14-electron cation [Rh(PPh3)3]+ is more electron-rich than expected, as a result of coordination of a C=C bond in one phenyl group, opened the way to a search for more examples of this behavior. We used DFT calculations and energy decomposition analysis to study this M-η2-arene interaction and to calculate its strength. For this purpose, we have chosen two formally unsaturated complexes, viz. [Mo(η5-C5H5)(CO)2(PPh3)]+ (1) and [Ru(η5-C5H5)(binap)]+ (2). In the former complex, the PPh3 ligand can be easily moved away from the metal, destroying the Mo-η2-arene interaction, while in 2 this is achieved by a distortion of the Binap ligand. The experimental parameters, namely the distortion of the aryl-containing ligand, have been well reproduced by the calculated coordination geometry; the M-η2-arene interaction was estimated as 13.4 kcal mol-1 for Mo and 21.4 kcal mol-1 for Ru. The energy decomposition analysis revealed the formation of a covalent bond between the metal and the C=C bond, which made the global process favorable, regard- less the energy required to reorganize the geometry of the ligand in the new environment.

Keywords: Rhodium; Ruthenium; Molybdenum; Arene complexes; Energy decomposition analysis (EDA); DFT calculations; Binap; Phosphine ligands; Half-sandwich complexes.

References: 45 live references.