The Chemical Meaning of an Electrochemically Quasireversible Process

However, how significant can such geometrical reorganizations be From a qualitative viewpoint we can roughly relate the extent of structural reorganization to the departure of the peak-to-peak separation from the theoretical value of 59/n mV, expected for a reversible process. 

In this connection, let us consider the following example (which will be discussed further in Chapter 5, Section 7), which illustrates the case of a significant, but not too important, structural reorganization  

In acetonitrile solution, the Cu Cu1 reduction of [CunL]2+ appears as a quasireversible process, giving rise to a forward-backward peak-system with AEp = 114 mV, at a scan rate of 0.1 V s l. 

In contrast, let us examine a case of very important structural consequences. As we will discuss in Chapter 7, Section 2.4, the carbonyl cluster [Os6(CO)18] undergoes a two-electron reduction with marked features of electrochemical quasireversibility AEp = 255 mV at 0.01 Vs 1. 

We must conclude that the marked electrochemical quasireversibility is due to the remarkable geometrical reorganization from the bicapped tetrahedron of [Os6(CO)18] to the octahedron of [Os6(CO)i8]2 occurring upon the two electron addition. 

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