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Electro‐ and Magnetocommunication in [5,5]Ditrovacenyls, [(η 7 ‐C 7 H 7 )V(η 5 ‐C 5 H 4 ‐X‐η 5 ‐C 5 H 4 )V(η 7 ‐C 7 H 7 )], Mediated by the Spacers X=( Z )CHCH, ( E )CHCH, >CCH 2 , CH 2 CH 2 , and CH 2
Author(s) -
Elschenbroich Christoph,
Plackmeyer Jörn,
Nowotny Mathias,
Behrendt Andreas,
Harms Klaus,
Pebler Jürgen,
Burghaus Olaf
Publication year - 2005
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200500492
Subject(s) - geminal , hyperconjugation , chemistry , crystallography , electron paramagnetic resonance , hyperfine structure , vicinal , paramagnetism , redox , electron transfer , stereochemistry , nuclear magnetic resonance , atomic physics , molecule , inorganic chemistry , physics , condensed matter physics , organic chemistry
Five new paramagnetic dinuclear complexes containing [5]trovacenyl groups, (η 7 ‐C 7 H 7 )V(η 5 ‐C 5 H 4 ), have been prepared and characterized, including by single‐crystal X‐ray diffraction. As intervening spacers, ethenediyl units in the geminal and vicinal ( Z )‐ and ( E )‐bridging modes as well as methanediyl and ethanediyl units have been included with the aim of studying their propensity to transmit electric and magnetic information. It is found that redox splitting of consecutive electron‐transfer steps is resolved for reduction (0→1−→2−) only, unsaturation of the C 2 bridge not being requisite, since the CH 2 CH 2 spacer also gives rise to a small redox splitting. Magnetic communication is quantified in terms of the exchange coupling constant J , accessible from the EPR hyperfine pattern in solution and from magnetic susceptometry in the solid state. The results obtained from these methods generally differ; this fact is not surprising in view of conformational differences in the respective states of aggregation. It is concluded that orientation‐dependent mechanisms of spin–spin interactions (π‐orbital overlap, hyperconjugation) contribute extensively although, as implied by sizeable J values for CH 2 and C 2 H 4 linked di[5]trovacenyl groups, coupling mediated by the σ‐orbital chain must also be considered.