Charge Transfer Assisted Ferromagnetic Coupling Observed in an Ion-Radical Salt of a Cross-Cyclophane TTF-Based Donor

Abstract

The ferromagnetic interaction was observed in a conducting ion-radical salt of a TTF-based cross-cyclophane type dimeric donor.

Current-Induced Low-Resistance State and Its Crystal Structure of a TTF-Based Dimeric Donor Salt

“…The ion-radical salt 1 ·Br·(TCE) 2 turned out to be a semiconductor, and the conductivity of the salt exhibited anisotropy5.7 × 10 -3 S·cm -1 (activation energy Δ E = 0.24 eV) within the ab plane and 1.3 × 10 -4 S·cm -1 (Δ E = 0.28 eV) along the c -axiswhich was consistent with the crystal structure . The ion-radical salt showed paramagnetic behavior with a Curie constant of 0.375 emu·K·mol -1 for the composition of 1 ·Br·(TCE) 2 , which suggests that the moderate conductivity of this salt can be explained by a hopping mechanism . According to the crystallographically nonequivalent structure of two TTF units and to the poor conductivity of the salt, the 1 ·Br·(TCE) 2 salt can be classified as a class I complex.…”

Bi-TTF, Bis-TTF, and Related TTF Oligomers

“…In contrast to eclipsed TTF cyclophanes, orthogonal bis-TTFs with a quadruple linkage have been prepared and are called crisscross bis-TTFs. ,, In 1995 Ostubo's group 134 and Sugawara's group 135 independently reported the first examples of crisscross bis-TTFs 161a − d . X-ray analysis of 161c showed that two TTF moieties overlap each other in a crisscross manner.…”

“…Although 161c only showed two two-electron redox waves, the cyclic voltammogram of 161d exhibited interesting behavior, i.e., a single wave for the first two-electron oxidation and a split wave for the second one. Recently, interesting properties of the ion-radical salt derived from 161b have been reported 135e…”

Molecular Electrochemistry of Cyclophanes

“…Again, the steric constraints appear highly important. In some cases, radical ionic intermediates of the oxidation process were electrocrystallized [59,60] resulting in materials with interesting, e.g. ferromagnetic [60] behavior.…”