Département de chimie moléculaire

Rotational motions of ferrocene-based carousels were achieved by electron transfer centered on $π$-dimerizable 4,4'-bipyridinium substituents introduced on both cyclopentadienyl rings through covalent linkers of different size, geometry, and flexibility. Detailed spectroscopic, electrochem., and theor. analyses demonstrate that rigid and fully conjugated linkers allow the quant. formation of intramol. $π$-dimers resulting from optimized orbital overlaps within the HOMO of the electrochem. generated bis-radical species. The tetra-cationic charge-repelled conformers, the self-assembled $π$-dimers, and their electron triggered interconversions were studied by UV-visible, NMR, and ESR spectroscopy, electrochem., x-ray diffraction anal., and theor. calcns. These studies support the conclusion that the rotation of both cyclopentadienyl rings in ferrocene can be controlled electrochem. using noncovalent reversible interactions arising from $π$-radical coupling processes. [on SciFinder(R)]