Stabilizing Radical Cation and Dication of a Tetrathiafulvalene Derivative by a Weakly Coordinating Anion

Abstract

After the chemical oxidation of the neutral tetrakis(methylthio)tetrathiafulvalene (TMT-TTF, 1) by specific oxidation agents with weakly coordinating anion, [Al(ORF)4](-) [ORF = OC(CF3)3], the radical cation TMT-TTF(•+) (1(•+)) and dication TMT-TTF(2+) (1(2+)) were successfully stabilized and isolated. All the compounds are well-soluble in some solvents and have been systematically investigated by absorption spectra, (1)H NMR, electron paramagnetic resonance (EPR) measurements. Their crystal structures and electronic properties have been studied in conjunction with theoretical calculation. The synthetic approach for chemical oxidation by specific salts of weakly coordinating anions is useful for stable radical cations of tetrathiafulvalene (TTF) and its derivatives in both solution and solid state, which will extend the further research, including structure-property relations on stable radicals for TTF derivatives and new functional materials based on them.

Reversible Switching of Organic Diradical Character via Iron-Based Spin-Crossover

“…These bonds are markers for the oxidation state of TTFtt n – , where similar increases in the C3–C3′ bond length and decreases in the C3–S3/4 bond lengths of ∼0.02 Å are correlated to the change from TTFtt 3–· to TTFtt 2– , potentially suggesting that the geometric changes at Fe and the TTFtt n – ligand are due to a charge-transfer-induced spin transition (Table S1). − Theory and experiment, however, suggest that these changes instead arise from increased diradical character on TTFtt 2– upon cooling from 2-HT to 2-LT , leading to a differential population of C–C and C–S π orbitals (see below). In sum, the structural data on 2 support an Fe-centered spin transition with additional electronic structure changes of the TTFtt 2– ligand.…”

Tuning Electrical‐ and Photo‐Conductivity by Cation Exchange within a Redox‐Active Tetrathiafulvalene‐Based Metal–Organic Framework

“…The central C⋅⋅⋅C bond length and the dihedral angle of the TTF core in TTF derivatives are known to be charge‐sensitive . The neutral TTF undergoes two one‐electron oxidations to TTF .+ and TTF 2+ and is accompanied by the conformational changes . Generally, the shorter C⋅⋅⋅C distance implies better conjugation degree for TTF‐based frameworks .…”

Atmospheric Nitrogen Fixation via a Porous Coordination Polymer Platform with Bridging Dinitrogen Anions

“…The generalized gradient approximation (GGA) method together with the Perdew-Burke-Ernzerhof (PBE) as the exchange-correlation functional 33 , and the ultrasoft pseudopotential were employed in both geometry optimizations and electronic property calculations. The Grimme method was applied to take the van der Waals interactions into account 34,35 . The PBC model with a cell size of 12.4 × 16.3 × 38.9 Å 3 , was employed to model the systems of NJUZ-1.…”