AbstractReaction of (dibromoboryl)ferrocene (1) with 1 equiv. of the diazabutadiene tBuN=CH–CH=NtBu, and subsequent reduction of the obtained borolium salt 2 with sodium amalgam, affords the first ferrocenyl‐functionalized 1,3,2‐diazaborole (3). Similarly, 1,1′‐bis(dibromoboryl)ferrocene (4) can be transformed into compound 6, which contains two diazaborolyl substituents at the ferrocene core. Treatment of precursors 1 and 4 with 1,2‐bis(tert‐butylamino)ethane in the presence of Et3N gives rise to the formation of the diazaborolidine derivatives 13 and 14. 1‐Dibromoboryl‐3‐methylcymantrene (7) was also treated with tBuN=CH–CH=NtBu to give the borolium salt 8, which was subsequently reduced to the 2‐cymantrenyl‐diazaborole 9. Treatment of 7 with tBuN(H)CH2CH2N(H)tBu in the presence of Et3N furnished the corresponding 2‐cymantrenyl‐diazaborolidine 15. The novel compounds were characterized by elemental analyses and various spectroscopic techniques (IR; 1H, 13C, and 11B NMR; MS). The molecular structures of 3, 6, and 15 were elucidated by X‐ray diffraction analyses. Cyclovoltammetric studies of the ferrocene derivatives at high scan rates show features of a quasireversible oxidation at the iron center. The heterocyclic groups serve as electron donors, considerably lowering the oxidation potential of the central iron atoms when compared to the parent compound ferrocene. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)