Ruthenium redox with complexes

A ruthenium(VI) nitrido complex containing a tetrapyrrolic macrocycle ligand, [Ru (N)(L)] (82) (H4L = mcio-octamethylporphyrinogen), has been synthesized by the reaction of diphewldiazomethane with [Ru"(L)] , which is prepared from [Ru(cod)(Cl)2] and Na4(L) 4THF. X-ray crystal studies reveal that [Ru (N)(L)] has a Cjv symmetry, and it has the usual saddle conformation, with the metal atom displaced 0.482 A out of the N4 mean plane. The reactivities and redox chemistry of this complex are summarized in Scheme 12 (see also Section 5.6.5.2). 

As discussed above for ferrocene derivatives, small water-soluble ruthenium and osmium complexes are good candidates for redox enzyme catalysis mediation for their reversible (II/III) behavior and relative stabiKty in the two-oxidation state in water. The alteration of the aromatic rings is a means of tuning of the redox potential/structure characteristics of the complexes, which is important for efficient redox enzyme mediation [75, 76]. Table 1 gives the redox potentials in acetonitrile of a series of neutral osmium(II) dichloride complexes with different substituted ligands [77]. 

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