Delocalized ligands

The difference between the two extremes is essentially that, in the former, the Re retains its valence electrons in its d orbitals whereas in the latter it loses 6 of them to delocalized ligand orbitals. In either case paramagnetism is anticipated since rhenium has an odd number of valence electrons. The magnetic moment of 1.79 BM corresponding to 1 unpaired electron, and esr evidence showing that this electron is situated predominantly on the ligands, indicates that an intermediate oxidation state is involved... 

In the context of this section, the electron-delocalized ligand 71-allyl (12) is an t donor and it is well known that allylic hahdes react with PdCl2 to form a hw-t -complex 19 (see the 3D model 20)." Complexes, such as 19, react with nucleophiles to give the corresponding coupling product (10-60)." The... 

Inner Transition Metal Complexes With Chains of Metal Atoms 103 9.2.12.1. Compounds Containing Nickel, Palladium, and Platinum Chains 9.2.12.1.4. Halogen-Oxidized Complexes Containing 7t-Delocalized Ligands. 

Halogen-Oxidized Complexes Containing n-Delocalized Ligands. 

Halogen-Oxidized Complexes Containing -Delocalized Ligands. 

The reductive electrochemistry of several Ni complexes of unsaturated dithiolate ligands has been examined. On the basis of the electrochemical redox potentials, EPR spectral evidence, and SCF calculations, these reduction products are best formulated as Ni complexes for dithiocarbamate and 1,2-dithiolene ligands, and as Ni stabilized ligand-radical anions for dithiodiketonate species. It is often difficult to assign electron-density distributions within a molecule, particularly with delocalized ligands such as dithiolenes. 

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