Head-on versus Side-on [5−5]Bitrovacenes Featuring Benzene and Naphthalene Units as Spacers: How π-Stacking Affects Exchange Coupling and Redox Splitting

Autor:	Olav Schiemann, Christoph Elschenbroich, Jürgen Pebler, Olaf Burghaus, Matthias Wolf, Klaus Harms
Rok vydání:	2002
Předmět:	Organic Chemistry Exchange interaction Stacking Photochemistry Redox law.invention Inorganic Chemistry chemistry.chemical_compound Electron transfer Crystallography chemistry law Physical and Theoretical Chemistry Cyclic voltammetry Benzene Electron paramagnetic resonance Naphthalene
Zdroj:	Organometallics. 21:5810-5819
ISSN:	1520-6041 0276-7333
Popis:	The biradicals 1,8-di([5]trovacenyl)naphthalene (6), 1,5-di([5]trovacenyl)naphthalene (7), and 1,3-di([5]trovacenyl)benzene (8) and the monoradical 1-[5]trovacenylnaphthalene (9) have been prepared and studied by means of single-crystal X-ray diffraction (6, 8, 9), cyclic voltammetry, EPR spectroscopy, and magnetic susceptometry. Comparison of the magnetic properties of 6−9 reveals that π-stacking, as encountered in 6, largely enhances exchange interaction between the two singly occupied V(3dz2) orbitals. The effect of π-stacking on the electrochemical properties, as manifested in the redox splitting between consecutive electron transfer steps, is less pronounced. Redox splittings δE1/2 for consecutive reductions exceed those for oxidations of binuclear trovacenes, δE1/2(2+/+, +/0) being apparent for π-stacked 6 only. Because of the orthogonality of the metal-centered redox orbitals V1(dz2) and V2(dz2) and the η5-cyclopentadienyl π-orbitals, electro- and magnetocommunication are indirect processes. Electr...
Databáze:	OpenAIRE
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