Synthesis and characterization of a new pyrazine functionalized TTF derivative and crystal structure of its charge-transfer complex with iodine

The new donor ligand 4,5-bis(2-pyrazylmethylsulfanyl)-4′,5′-bis(cyanoethylthio)tetrathiafulvalene (1) has been synthesized and characterized. The electrochemical properties of the ligand have been investigated by cyclic voltammetry (CV) and 1 shows two reversible oxidation processes at E11/2=0.69VandE21/2=0.97V (in DCM, versus Ag/AgCl). The charge-transfer complex (12)2+[(I2)3/2I−]2 · 2CH2Cl2 has been prepared by layer diffusion and characterized by X-ray crystallography. The oxidized ligand forms head-to-tail π-dimers which are embedded in layers of a 2D polyiodide network. The separation of these dimers by the anionic network and solvent molecules accounts for the insulating property of the charge-transfer complex.

Graphical abstractThe unique crystal structure of a charge transfer complex of new donor 1 with I2 shows that the radical cation forms π-dimers embedded in layers of a 2D iodide network.Figure optionsDownload full-size imageDownload as PowerPoint slide