Hybrid Organic–Inorganic Conductor Coupled with BEDT-TTF and Photochromic Nitrosyl Ruthenium Complex

An organic–inorganic hybrid system coupled with an organic conductor and photosensitive transition metal complex has a possibility to exhibit fascinating multifunctionalities, such as photo-controllable conductor. To explore multifunctional materials, such as a photo-tunable conductor, we prepared (BEDT-TTF)4[RuCl5(NO)]·C6H5CN (BEDT-TTF: 4,5-bis(ethylenedithio)tetrathiafulvalene) by electrocrystallization, and investigated the structural and physical properties. X-ray crystallographic analysis shows alternate layers of BEDT-TTF cations and ruthenium complex anions. The organic layer is formed by the dimers of BEDT-TTF arranged almost perpendicular to each other, which indicates that the donor arrangement of this salt belongs to κ-type. Based on the Raman spectrum, the oxidation state of the BEDT-TTF molecules is estimated to be +0.7. X-ray structural analysis and the EPR spectra suggest that there is a partial electron transfer from BEDT-TTF to the π* orbital of NO ligand in [RuCl5(NO)] through a short intermolecular contact. A magnetic susceptibility measurement and the EPR spectra proved this compound to be a localized spin system due to a strong on-site Coulomb repulsion, which results in the semiconducting behavior of this compound.