Carbon-based scorpionates

The application of the initial Lever model to nr-sandwich or r-half-sandwich complexes requires the assumption of the validity of Eq. 50.3 to such types of complexes and of the and /jyi values quoted for the metal redox couples in octahedral-type complexes. Although full confirmation of this hypothesis requires the consideration of wider series of complexes, it has been applied by us [32] to half (or full)-sandwich complexes bearing itt-aromatic (benzene or p-cymene) ligands or polydentate boron-based or carbon-based scorpionate-type ligands. For the estimate of the corresponding El values for such polytopal ligands (based on Eq. 50.3), the El values of the co-ligands in their complexes should be known, as well as the and 7, values of their metal redox couples. 

In contrast to boron-based scorpionates, such as (pyrazolyOborate and derivatives, those based on carbon, namely tm(pyrazolyl)methane, HC(pz)3, and hydrosoluble-derived ones (Scheme 2.2a), are still underexplored, in spite of then-potential, when suitably functionalized, to form water-soluble complexes. A good example is the sulfonate derivative, that is, tm(pyrazolyl)methane sulfonate (Tpms), which is hydrolytically stable over a wide pH range and leads to sandwich... 

The present contribution exemplifies a strategy for efficient and highly selective oxidation reactions of industrial interest directed toward organic synthesis, using catalytic systems based on transition metal complexes bearing tris(pyrazol-l-yl)methane-type scorpionates, RC(R pz)3 (pz = pyrazol-l-yl R = H or substituent at the methine carbon R = H or substituent at the pz ring Fig. 22.1). 

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