Organometallic radicals metallocenes

The first metallocene radical isolated was cobaltocene—the importance of which is highlighted by its inclusion in an early preparative organometallic text.12 This 19 e complex remains a reagent of choice for electron transfer reactions in nonaqueous solvents.13 A key question in delocalized organometallic radical complexes is where is the unpaired electron. An early example of this is RhCp2 (Cp = T 5-C5H5), which... 

Electronic Effects in Metallocenes and Certain Related Systems, 10, 79 Electronic Structure of Alkali Metal Adducts of Aromatic Hydrocarbons, 2, 115 Fast Exchange Reactions of Group I, II, and III Organometallic Compounds, 8, 167 Fluorocarbon Derivatives of Metals, I, 143 Free Radicals in Organometallic Chemistry, 14, 345 Heterocyclic Organoboranes, 2, 257... 

Coordination chemistry has become a powerful tool for the control and the living nature of radical polymerization [79,80]. Various examples show that the role of initiator and counter radical can be played by organometallic species with an even number of electrons. Besides aluminum complexes used by Matyjaszewski, several other transition metals, metallocenes, and organolan-thanides with various ligands have been studied in controlled radical polymerization [79-97]. In some cases, a controlled polymerization was achieved [81,83-85,87,90-94,97]. However, the mechanism of the polymerization is not always known and it may happen that heterolytic cleavage of the active bond... 

F. J. Smentowski Characterisation of organometallic compounds by electron spin resonance, pp. 481 651 (1236). Particularly useful for an extensive literature review. Mainly Main Group elements and anion radicals, but with important section on metallocenes. 

Finally, in the search for novel magnetic molecules useful in molecular electronics, metallocenes were used as intramolecular magnetic couplers between pure organic radicals with the aim of tuning the magnetic properties of the molecule by playing with the redox properties of these organometallic couplers. 

Delocalization of c -electron spin from a transition metal has been used to study structure, equilibria, and reactions of complexes, particularly ligand exchange and solvation. Other applications are to organometallics, such as metallocenes, metallobiomolecules such as porphyrins (haemoglobins, cytochromes), iron-sulfur clusters, and so on. Organic radicals such as nitroxides or aromatic radical ions are useful spin probes also. The field of paramagnetic NMR spectroscopy has been reviewed biennially. ... 

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