Rhenium, cyclometalated complexes

Sutton has reported a pentamethylcyclopentadienyl rhenium dinitrogen complex that activates benzene (Eq. 29) [114]. The intermediate involved is similar to that described above in studies by Bergman [92]. In the absence of a reactive solvent, cyclometallation was observed. 

Luminescent organometallic complexes used for cell imaging can be divided in two main families, namely (i) carbonyl complexes, most commonly octahedral rhenium c-tricarbonyl derivatives incorporating a polypyridine ligand and (ii) cyclometalated complexes such as iridium and platinum derivatives containing the ubiquitous 2-phenylpyridine unit (complexes 1-3 in Scheme 11.2). 

Rhenium dinitrogen phosphine and phosphite complexes give products through intramolecular C-H activation upon ultraviolet (UV) irradiation in hydrocarbon solvents. For example, the agostic complex 88 identified by IR spectroscopy decays to stereoisomeric cyclometallated products [Eq. (6.68)]. Analogous transformations were observed for phenoxy and phenyl derivatives. 

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