Ferrocenes basic properties

The lack of basic properties of bis-n-benzene chromium compared to those of ferrocene may be due in part to the reduced availability to acceptor ligands of the e2g electrons which, in -arene complexes, are quite important (see above). It is worth noting that no bent bis- -arene complexes are presently known (e.g., no ( i-C[Pg.178]

Several additional studies have confirmed interannular electronic interactions in ferrocene. Early investigations by Nesmeyanov and coworkers and by others demonstrated the electron-donor properties of the ferrocenyl group (71). Aminoferrocene, for example, is approximately 20 times as strong a base as aniline, while benzoic acid is several times more acidic than ferrocenecarboxylic acid. Moreover, acidities and basicities of this sort are markedly affected by substituents on the opposite cyclopentadienyl ring. 

In terms of basicity, pA s of the two drugs indicate that FQ is less basic than CQ (Table 1, [129]). Crystal structure of FQ (Fig. 23) shows the presence of a strong internal hydrogen bond between the anilino (Nil) group and the tertiary amino N(24) [128]. This, together with the electron donating properties of the ferrocene moiety, should explain the decreased pKa values. 

The specific properties of ferroquine, certain of which encompass the structure-function relationship proposed for chloroquine [140] are the following. (1) Maintenance of a 4-aminoquinoline entity for vacuolar accumulation by pH trapping and haematin association (2) A side chain comprising a basic amino group, to provide strong antiplasmodial activity (3) A ferrocenyl group for its lipophilic (log Po/w=3.3) and redox (ferrocene/ferricinium Eg =+460 mV) properties (4) A rapid and cheap synthetic method, involving few steps. 

Chiral phosphorus-containing dendrimers which have ferrocene molecules at the periphery have been the subject of work by Majoral and co-workers. These materials will have obvious applications in catalysis. Layer-by-layer dendrimers, which are built up containing chiral ferrocenylphosphine molecules, have also been prepared, and their chiroptical and electrochemical properties have been investigated. A recent article covers the basic chemistry of ferrocene-containing liquid-crystalline polymers which stems from the extensive work of Deschenaux, who essentially pioneered the area. A ferrocene end-capped dendrimer has also been used in carbon monoxide sensing. The actual dendrimer, shown as 19, has 48 ferrocene molecules on the periphery. 

A very recent trend concerns the use of nTs as the basic unit for building more sophisticated molecular architectures with properties specifically tailored to the development of molecular electronic devices. Thus, end-capped nTs functionalized by ferrocene (78) or viologen (79) have been described. These compounds exhibit the specific electrochemical responses of both the attached... 

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