Electronic structure and properties of transition metal-benzene complexes

A comprehensive theoretical study of the geometries, energetics, and electr onic structure of neutral and charged 3d transition metal atoms (Mj interac ting with benzene molecules (Bz) is carried out using density functional th eory and generalized gradient approximation for the exchange-correlation po tential: The variation of the metal-benzene distances, dissociation energie s, ionization potentials, electron affinities, and spin multiplicities acro ss the 3d series in MBz complexes differs qualitatively from those in M(Bz) (2). For example, the stability of Cr(Bz)(2) is enhanced over that of CrBz by almost a factor of 30. On the other hand, the magnetic moment of Cr(Bz)( 2) is completely quenched although CrBz has the highest magnetic moment, na mely 6 mu (B), in the 3d metal-benzene series. In multidecker complexes inv olving V-2(Bz)(3) and Fe-2(Bz)(3), the metal atoms are found to couple anti ferromagnetically. In addition, their dissociation energies and ionization potentials are reduced from those in corresponding M(Bz)(2) complexes. All of these results agree well with available experimental data and demonstrat e the important role the organic support can play on the properties of meta l atoms/clusters.