[7−7]- versus [5−5]Bitrovacene: How Linkage Isomerism Affects Exchange Coupling and Redox Splitting1

Autor:	Christoph Elschenbroich, Olaf Burghaus, Jörn Plackmeyer, Klaus Harms, Jürgen Pebler
Rok vydání:	2003
Předmět:	Steric effects Stereochemistry Organic Chemistry Vanadium chemistry.chemical_element Ring (chemistry) Redox Spectral line law.invention Inorganic Chemistry Crystallography chemistry Cyclopentadienyl complex law Physical and Theoretical Chemistry Linkage isomerism Electron paramagnetic resonance
Zdroj:	Organometallics. 22:3367-3373
ISSN:	1520-6041 0276-7333
Popis:	Thermal rearrangement of dicycloheptatriene C 1 4 H 1 4 and subsequent reaction with (η 5 -cyclopentadienyl)(tetracarbonyl)vanadium affords [7-7]bitrovacene, μ-η 7 :η 7 -C 1 4 H 1 2 [(η 5 -C 5 H 5 )V] 2 (8 . . ). Sterically induced avoidance of a planar μ-η 7 :η 7 -heptafulvalenediyl bridge leads to a complicated packing pattern of varyingly twisted units of 8" which generates a huge unit cell (Z = 72), in stark contrast to the isomer 7 . . , for which Z = 2 applies. The isomers 8" and 7" also differ with regard to the extent of intervanadium electro- and magnetocommunication. Redox splittings δE 1 / 2 of consecutive ET steps are considerably larger for 8 . . , compared to 7 . . , thereby reflecting the higher contribution the larger ring makes to the SOMO. The higher spin density at the C 7 compared to the C 5 carbon atoms, which governs the EPR spectra, effects a pronounced gradation of the exchange coupling parameter determined by magnetic susceptometry: J(7 . . ) = -2.8, J(8 . . ) = -24.1 cm - 1 .
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::9c4adbe2cb581d20f75a5ff4c7951143 https://doi.org/10.1021/om020717q Zobrazit plný text záznamu