Tuning the electronic structure of diboradiferrocenesCCDC reference numbers 669587–669589. For crystallographic data in CIF or other electronic format see DOI: 10.1039/b718789k.

A series of diboradiferrocenes with different aryl substituents was prepared through reaction of B,B-dichlorodiboradiferrocene 2 with arylcopper and Grignard reagents. The mesityl and pentafluorophenyl derivatives, 3–Mes and 3–Pf, were fully characterized by multinuclear NMR, MALDI-TOF mass spectrometry and X-ray crystallography, and their electronic structure was examined by UV-visible spectroscopy and cyclic voltammetry. A comparison of the data for 3–Mes and 3–Pf with those of the parent compound 3–Ph revealed the importance of electronic and steric effects of the substituents on the electronic structure of the compounds and ultimately the degree of electronic interaction between the two ferrocene moieties. An unusually large redox splitting of ΔE = 703 mV was determined from the cyclic voltammogram of 3–Pf. [ABSTRACT FROM AUTHOR]