Ferrocene derivatives VII. NMR spectroscopic investigations of bridged ferrocenes☆

An unexpected reactivity of ferrocenedicarboxaldehydes 1 and 2 with primary amines in classical reductive amination conditions gives two new N-(substituted)-2-aza-[3]-ferrocenophanes in 1,1′ and in 1,2 series.

The purpose of this chapter is to report on ferrocenes, which contain heterocyclic systems fused either to the ferrocene or as a substituent on the ferrocene. Ferrocene is theoretically capable of forming three types of cyclized structures (1, 2, and 3); only examples of 1 and 3 have been reported, with a heteroatom in the chain connecting the 1 and 2 carbons of one five-membered ring and in the bridge between the 1- and 1'-positions of ferrocene. The two ferrocenes containing a heterocyclic ring fused to the ferrocenes discussed here are ferroceno heterocyclic compounds and bridged heterocyclic compounds. The chapter discusses various ferrocenyl heterocyclic compounds namely, nitrogen-containing rings (compounds containing a heteronitrogen); nitrogen and other heteroatoms in ring (those with nitrogen and another heteroatom); oxygen-containing rings (those with a heterooxygen or an oxygen and another heteroatom other than nitrogen); and sulfur-containing rings (those with a heterosulfur but no nitrogen or oxygen). Other heterocyclic metallocenes discussed in the chapter are divided in two categories those in which the heterocyclic group is a substituent on the metallocene, such as heterocyclic compounds containing cyclopentadienylmanganese tricarbonyl, and those in which a heteroatom is in a ring of the metallocene, such as in azaferrocene. Compounds of potential medicinal interest are also focused in the chapter and ferrocene itself and a variety of ferrocene derivatives have been studied as potential hematinic agents. A variety of ferrocene derivatives have been used for the labeling of immunoproteins and related functions.