The Crystal Structure and Intramolecular Electron Transfer of 1′,1'″-Diethylbiferrocenium Triiodide at 298 and 140 K

Abstract

Abstract The crystal structure of 1′,1'″-diethylbiferrocenium triiodide, (EtFcFcEt)+ I3−, was determined by means of X-ray diffraction. The crystals at 298 and 140 K are found to be monoclinic, with the P21⁄c space group and with Z=2. At 298 K, a=9.7557(10), b=9.9772(12), c=13.8216(13) Å, β=107.625(9)°, and U=1282.18(23) Å3, while at 140 K, a=9.6931(17), b=9.8065(22), c=13.7373(19) Å, β=107.642(15)°, and U=1244.4(4) Å3. The structures are refined to R=0.049 at 298 K and R=0.036 at 140 K. The (EtFcFcEt)+ cations and I3− anions sit on a crystallographic center of symmetry both at 298 and at 140 K, and the two ferrocenyl(Fc) units are crystallographically equivalent. The ethyl group in each ethylcyclopentadienyl(EtCp) group is not parallel to the fulvalene moiety, but the terminal CH3 group moves away with the 60° inclination from the Cp plane. An appreciable interaction seems to exist between the Cp ring of the cation and the I3− anion along the a+c⁄2 direction, but the interaction among the cations along the a axis seems to be so weak as to be negligible.