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Charge‐Transfer Salts of 6,6‐Dicyanopentafulvenes: From Topology to Charge Separation in Solution
Author(s) -
Finke Aaron D.,
Zalibera Michal,
Confortin Daria,
Kelterer AnneMarie,
Mensing Christian,
Haberland Sophie,
Diederich François,
Gescheidt Georg
Publication year - 2018
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.201802486
Subject(s) - cobaltocene , chemistry , chromophore , metallocene , redox , acceptor , charge (physics) , electron paramagnetic resonance , photoinduced charge separation , ground state , solvent , crystallography , polymerization , photochemistry , inorganic chemistry , organic chemistry , nuclear magnetic resonance , polymer , catalysis , atomic physics , physics , quantum mechanics , condensed matter physics , photocatalysis , artificial photosynthesis
6,6‐Dicyanopentafulvene derivatives and metallocenes with redox potentials appropriate for forming their radical anions form highly persistent donor–acceptor salts. The charge‐transfer salts of 2,3,4,5‐tetraphenyl‐6,6‐dicyanofulvene with cobaltocene ( 1⋅ Cp 2 Co) and 2,3,4,5‐tetrakis(triisopropylsilyl)‐6,6‐dicyanofulvene with decamethylferrocene ( 2⋅ Fc*) have been prepared. The X‐ray structures of the two salts, formed as black plates, were obtained and are discussed herein. Compared with neutral dicyanopentafulvenes, the chromophores in the metallocene salts show substantial changes in bond lengths and torsional angles in the solid state. EPR, NMR, and optical spectroscopy, as well as superconducting quantum interference device (SQUID) measurements, reveal that charge‐separation in the crystalline states and in frozen and fluid solutions depends on subtle differences of redox potentials, geometry, and on ion pairing. Whereas 1⋅ Cp 2 Co reveals paramagnetic character in the crystalline state and in solution, compound 2⋅ Fc* shows a delicate balance between para‐ and diamagnetism, depending on the temperature and solvent characteristics.