Ferrocene derivatives Nesmeyanov

The oxidation potentials of substituted ferrocenes are, perhaps not unexpectedly, found to be a sensitive function of the number and type of ring substituents. The formal oxidation potentials of a considerable number of mono- and disubstituted ferrocene derivatives have been determined titrimetrically 19, 20, 31, 35, 38), as well as by chronopotentiometry 5, 25, 27, 28, 29, 62, 63) and polarography 2, 39, 56, 57, 58). The oxidation potentials of these substances appear to correlate rather well with disubstituted ferrocenes, although Nesmeyanov and his coworkers have more recently claimed 35) that a better correlation is obtained with the Taft constants 53, 54). 

Nesmeyanov et a/.545 used a mixture of ferrocene, deuterated trifluoroacetic acid and benzene in the molar ratios 1 2 20 in a preliminary investigation of the reactivity of ferrocene and its derivatives. At 25 °C, rate coefficients were 1,620 x 10-7 (ferrocene) and 19.3 xlO-7 (acetylferrocene). In a subsequent publication by Alikhanov and Shatenshtein543 these values were altered to 1,600 x 10-7 and 1.5 x 10 7, respectively, and a value of 0.77 x 10"7 added for 1,1-diacetylferrocene. Under the same conditions, toluene gave a value of 0.3 x 10-7 so that the activating effects of these compounds relative to benzene can be approximately determined. 

Nesmeyanov et a/.546 have also measured the effects of substituents in deuteration of ferrocene by deuterated trifluoroacetic acid in dichloromethane at 25 °C. Rate coefficients were measured for ferrocene and its derivative in a range of such acid mixtures, the composition of which was omitted, and in some cases the rate of exchange for ferrocene was calculated on the basis of a linear relationship between log and —H0. Results including the calculated knl values are given in Table 161. It should be noted that, in discussing those results, the authors quoted the incorrect partial rate factors for dedeuteration of toluene arising from the use of the incorrect data for benzene (see p. 199). This should be taken into account... 

Ferrocene organomercurials were also used to prepare a number of other derivatives, namely, halogen-, sulfur-, or selenium-containing compounds, biferrocenyl, or triphenylmethylferrocene [Nesmeyanov, Perevalova, 0. A. Nesmeyanova 258,259)]. Lithiation or sodium metalation provided even more versatile reagents, the reactions being used by other investigators as well. 

A.N. Nesmeyanov, N.A. Volkenau, and I.N. Bolesova, The interaction of ferrocene and its derivatives with aromatic compounds. Tetrahedron Lett. 1963, 25, 1725-1729. 

Although boranes still produce exciting new molecular species like water-stable B(C6Cl5)3 and associated one-electron reduced radical anions, most work in electroanalytical mechanisms is focused on boronie acid derivatives with a more or less strong interaction with a redox active reaction centre. The most literature-abundant redox active boronie acid is ferrocene-boronic acid (as synthesised first by Nesmeyanov ) with a range of selective redox label applications. 

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