Influence of Relativistic Effects on Bonding Modes in M(II) Dinuclear Complexes (M = Au, Ag, and Cu)
Paul Jerabek1, Beatriz von der Esch1, Hubert Schmidbaur2
1The New Zealand Institute for Advanced Study, Massey University , Private Bag 102904, 0632 Auckland, New Zealand.
Abstract:
The stability and bonding in dinuclear group 11 metal complexes (M = Au, Ag, and Cu) in their +2 oxidation state has been investigated by quantum chemical methods. Two model complexes were selected as representatives of different bonding situations in the dinuclear M(II) complexes, a direct metal-metal bond between two ligand stabilized monomers and ligand-mediated bridged dimer system, making them interesting for a direct comparison and to study the influence of relativistic effects. Relativity substantially stabilizes the direct metal-metal bonded system obtaining the sequence in M-M bond stability Au > Ag > Cu. In the ligand-bridged structure, an asymmetric bonding situation is obtained for gold, resulting in two stronger/covalent and two weaker/ionic bonds per gold atom. Here we observe the opposite trend in stability Cu > Ag > Au. Our analysis nicely corroborates with what is known from experimental observation.
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