Redox-active ligands ferrocenes

The octamethyl-1,1 -di (2 -pyridyl) ferrocene, redox-active ligand was used as an electrochemical sensor for Cd(II) and Zn(II) ions in acetonitrile [380]. 

Redox active ancillary ligands were first used to control lactide polymerizations using titanium complexes [51]. Very recently, Diaconescu and co-workers have reported derivatives of salen complexes incorporating a ferrocene unit which can be oxidized and reduced to switch the polymerization OFF and ON , respectively (Fig. 11) [52, 53],... 

The incorporation of 1,4-phenylenediamine as part of the crown ether produces redox-active macroscopic ligands. Macroscopic redox aetive ligands containing ferrocene-, tetrathiafulvalene- and quinone derivatives have been prepared and are discussed (2). 

Electrochemical and X-ray Structural Aspects of Transition Metal Complexes Containing Redox-Active Ferrocene Ligands... 

Finally, Hill et al reported the synthesis of vinylidene and allenylidene complexes of the types [TpRu( = C = CHR)(L)2] (L = PPh3 or L2 = 1,1 -bis(diphenylphosphino)-ferrocene R = Ph, C6H4Me), [TpRu( = C = C = CR2)(L)2] and TpRuCl( = C = C = CPh2)(PPh3). The eationie complexes underwent an unprecedented eoupling with dithiocarbamates, whieh led to metallacyclic vinyl and allenyl complexes (Seheme 34). Similar allenylidene eomplexes but featuring redox-active substituents and ligands based on ferrocene were reported by Hartmann et al ... 

Beer. P.D. Sikanyika, H. Blackburn, C. McAleer, J.F. Drew. M.G.B. Redox-responsive crown ethers containing a direct link between the ferrocene redox-active center and a benzo-crown ether—Crystal-structures of a ferrocene benzo-15-crow ii-5 ligand and of its sodium complex. J. Chem. Soc., Dalton Trans. 1990. 3295-3300. 

We have prepared and characterized a range of complexes of the new redox active Fctpy ligand, including [Fe(Fctpy)2][PF6]2 (blue), [Cu(Fctpy)2][PF6]2 (red) and [Ru(Fctpy)2][PF6]2- Each of these complexes shows two oxidation processes one is associated with the ferrocene substituent (+0.20, +0.30 and +0.22V respectively) and the other with the other metal centre (Fe, +0.8 IV, Co, -0.18V and Ru, +0.90V). These data have allowed us to define a Hammet redox active terminators into oligomers and into multiple helical systems. 

Cross-metathesis was recognized as a convenient route to introduce various functionalities into organometallic frameworks, initially including ferrocenes. For example, catalyst with a methylideneferrocenyl ligand was prepared by a stoichiometric reaction of vinylferrocene (4-1) with the Schrock catalyst (Scheme 12.21) [3]. Polymers with one ferrocenyl redox-active end group were obtained with this unique initiator. 

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