Rhodium electrochemical redox

Electrochemical redox reactions have been reported for triazenide complexes of iron 214), cobalt 214), and rhodium 43). 

Complex 9 (Scheme 43.3) can be reduced by different redox equivalents to the active rhodium(I) species 10 namely, by electrons, formate [37, 38], and hydrogen. This hydrido complex then transfers the hydride ion onto the nicotinamide. In electrochemical applications, TOFs in the range of 5 to 11 h-1 have been reported [31, 39]. It is noteworthy that this complex accepts NAD+ and NADP+ as substrates with the same efficiency and almost exclusively produces the 1,4-reduced cofactor (selectivity >99%). 

Finally, rhodium and iridium blue complexes have been also characterized, but no electrochemical studies have been carried out, as no redox couples seem to be accessible.14b... 

Fig. 23 Electrochemically driven d-LDH catalyzed enzymatic reduction of pyruvate to D-lactate using pentamethylcyclopentadienyl-2-2 -bipyridinechloro-rhodium(III) ([Cp Rh(bpy)Cl]Cl) as redox catalyst...

As only guanine moieties in the close vicinity of the electrode surface can undergo direct electrooxidation, soluble redox mediators such as rhodium or ruthenium complexes are sometimes used to shuttle electrons from guanine residues in distant parts of DNA chains to the electrode [20]. In such a case, we cannot speak more about the reagent-less technique. Nevertheless, the electrochemical reduction and oxidation of nucleobases are irreversible and thus do not allow reusability of biosensors. 

Very efficient reduction of NAD(P) with formate catalyzed by cationic rhodium complexes. /. Chem. Soc. Chem. Commun., 1150-1151 (d) Franke, M. and Steckhan, E. (1988) Tris(2,2 -bipyridyl-5-sulfonic add) rhodium(III), an improved redox catalyst for the light-induced and the electrochemically initiated enzymatic reduction of carbonyl compounds. Angeiv. Chem., Int. Ed., 27, 265-267 (e) Grammenudi, S., Franke, M., Vogde, F., and Steckhan, E. (1987) The rhodium complex of a tris(bipyridine) ligand - its electrochemical behavior and frmction as mediator for the regeneration of NADH from NAD. /. Ind. Phenom. Macrocycl. Chem., 5,695-707 (f) Hollmaim, F., Kleeb, A., Otto, K., and Schmid, A. (2005)... 

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