title: Redox control of rotary motions in ferrocene-based elemental ball bearings.
abstract: Rotational motions of ferrocene-based carousels have been 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, electrochemical, and theoretical analyses demonstrate that rigid and fully conjugated linkers allow the quantitative formation of intramolecular π-dimers resulting from optimized orbital overlaps within the HOMO of the electrochemically generated bis-radical species. The tetra-cationic "charge-repelled" conformers, the self-assembled π-dimers, and their electron triggered interconversions have been investigated by UV-vis, NMR, and ESR spectroscopy, electrochemistry, X-ray diffraction analysis, and theoretical calculations. These studies support the conclusion that the rotation of both cyclopentadienyl rings in ferrocene can be controlled electrochemically using noncovalent reversible interactions arising from π-radical coupling processes.
authors.affiliation: Laboratoire de Chimie Inorganique Rédox, Département de Chimie Moléculaire, Université Joseph Fourier/CNRS, Grenoble, France.
authors.forename: Adriana
authors.initials: A
authors.lastname: Iordache
authors.forename: Mircea
authors.initials: M
authors.lastname: Oltean
authors.forename: Anne
authors.initials: A
authors.lastname: Milet
authors.forename: Fabrice
authors.initials: F
authors.lastname: Thomas
authors.forename: Benoît
authors.initials: B
authors.lastname: Baptiste
authors.forename: Eric
authors.initials: E
authors.lastname: Saint-Aman
authors.forename: Christophe
authors.initials: C
authors.lastname: Bucher
mesh_terms: D003517:Cyclopentanes / Q000138:chemical synthesis / Q000737:chemistry; D005296:Ferrous Compounds / Q000737:chemistry*; D000075163:Metallocenes; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011725:Pyridines / Q000737:chemistry; D012399:Rotation
chemical_list: D003517:Cyclopentanes; D005296:Ferrous Compounds; D000075163:Metallocenes; D011725:Pyridines; C004998:ferrocene; C034306:4,4'-bipyridyl