N-ferrocenyl isonicotinamide, a redox-active 1D hydrogen-bonded chain structure capable of supporting a mixed-valent redox state

•N-ferrocenyl isonicotinamide was prepared in 28–61% yield.•The amide is twisted by 31.7° with respect to py and 9.7° to the attached Cp.•Forms 1D H-bonded chains through the amide and oriented along [010]•Forms a class III mixed valent state with alternating Fc & Fc+

N-ferrocenyl isonicotinamide was prepared in 28% isolated yield by the acetylation of aminoferrocence with isonicotinoyl chloride in THF and 61% isolated yield by HOBt mediated DCC coupling in CH2Cl2 and characterized by NMR, IR, ESI-MS, and UV-vis spectroscopy. The structure of Nferrocenyl isonicotinamide, C16H14FeN2O, at 100 K exhibits orthorhombic (Pbca) symmetry. The N-ferrocenyl isonicotinamide's amide group is twisted by 31.7° with respect to the py group and 9.7° relative to the attached Cp ring, in contrast to the planar structure observed for the isomeric (4- Pyridylaminocarbonyl)ferrocene. Adjacent isonicotinamide groups form 1D hydrogen bonded chains through the amide CO and NH groups; this H-bonding network is oriented along the [010] direction. Solid state cyclic voltammetry indicates that this hydrogen bonding network is capable of supporting a class III mixed valent redox state. In contrast, CH2Cl2 and MeCN solutions of the complex exhibit a Fc+/0 redox potential of 420-430 mV vs. Ag/AgCl.

Graphical abstractThe crystal structure of N-ferrocenyl isonicotinamide reveals that its amide group is twisted by 31.7° with respect to the py group and 9.7° to the Cp. Adjacent isonicotinamide groups form 1D hydrogen bonded chains through the amide. Solid state cyclic voltammetry indicates that the network can support a class III mixed valent redox state containing alternating Fc and Fc+ units.Figure optionsDownload full-size imageDownload as PowerPoint slide