Charge-Transfer Salts of Octamethylferrocenyl Thioethers with Organic Acceptors (TCNQ and TCNQF₄) and Trihalides (Br₃^- and I₃^-). Synthesis, Structure, and Physical Properties

Abstract

Six charge-transfer (CT) complexes containing three different octamethylferrocene derivatives (Fe(η5-C5Me4SMe)2, 1; Fe(η5-C5Me4StBu)2, 2; Fe(η5-C5Me4S)2S, 3) and TCNQ or TCNQF4, respectively (4−9), have been prepared and fully characterized. X-ray crystal structural studies of 4, 5, 7, and 9 have been carried out. The CT complexes 4 and 5, containing TCNQ, display stacks of acceptor molecules with noncommon donor/acceptor stoichiometries of 3:7 for 4 and 1:3 for 5, whereas the charge-transfer complexes 7 and 9, containing TCNQF4, display strongly interacting dimers of acceptor anions. The compounds 4−6 behave as semiconductors with room-temperature conductivities up to 3.5 S cm-1 for 6. Magnetic susceptibility measurements indicate strong antiferromagnetic interaction for the (TCNQF4)22- dimers in 7−9, the dimers being diamagnetic (S = 0) at room temperature. Antiferromagnetic interactions are also observed for the three compounds 4−6. To obtain more accurate Landé-g factors for the three possible cations from 1−3, the corresponding trihalogenide salts with Br3- (10−12) and I3- (13−15) were prepared and fully characterized. Their magnetic properties, only deriving from the cations, were measured, and X-ray crystal structural studies have been carried out for the compounds 11, 12, 14, and 15. For the two compounds containing the tert-butyl substituent (11 and 14), a DADA structural motif was observed, and with the trithiaferrocenophanium, chains (12) and networks (15) of alternating sulfur bridges and trihalogenide anions were observed.