1 Published: Chimia, Vol.59, p.504-510, 2005 Theoretical Studies on the Electronic Properties and the Chemical Bonding of Transition Metal Complexes using DFT and Ligand Field Theory M.Atanasov*, C.Daul Abstract The research activity within our laboratory of computational chemistry at the university of Fribourg is presented. In this review, we give a brief outline of a recently proposed Ligand Field Density Functional Theory (LFDFT) model for single nuclear and its extension to dimer transition metal complexes. Applications of the model to dinuclear complexes are illustrated for the interpretation of exchange coupling in the bis-µ- hydroxo-bridged dimer of Cu(II) and to the description of the quadruple metal-metal bond in Re 2 Cl 8 2- . Our analysis of the chemical bonding are compared with results obtained using other approaches: i.e. the Extended Transition State model and the Electron Localization Function. It is shown that the DFT supported Ligand Field Theory provides consistent description of the ground and excited state properties of transition metal complexes. Keywords: Density Functional Theory, Ligand Field Theory, Magnetic-Exchange Coupling, Transition Metal Dimer Complexes, Chemical Bonding, Electronic Absorption and Emission Spectra, Electron Localization Function. Correspondence: Prof.Dr.M.Atanasov Département de Chimie Departement für Chemie