Noninnocent ligands, description

The numerous properties of metallo-dithiolene complexes are a direct consequence of the fantastic redox interplay between the redox-active metal and the dithiolene ligand. A considerable amount of experimental evidence over the last 40 years has pointed to the fact that dithiolenes are highly noninnocent ligands (20, 86, 110, 113, 280-282). That is, they may be viewed in a valence bond description as existing somewhere between the extremes of neutral (dithione/dithiete) and dianionic (dithiolate) forms (Fig. 1). This variable formal... 

A number of paramagnetic Rh, Ir, Pd, and Pt complexes containing redox noninnocent radical ligands have been reported. These species are not always easily distinguishable from their redox tautomeric metal centered radical descriptions, as described in the introduction. 

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