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-C5Me4S t Bu)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)2 2- 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 Land é-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.

Interaction of I- and I3- with a Redox-Stable Cr(III)-Based Structural Surrogate for Photo-Oxidized “N3 Dye”

“…Again the closest non-hydrogen contact between the ions is between one of the terminal iodine atoms and a carbon of one of the bipyridine ligands (3.711 Å). For other structural examples in which there is evidence for a I 3 - /cation charge-transfer interaction, the reported interaction distances are between 3.70 and 4.11 Å . The relative positioning and separation of the I 3 - and bpy ligand strongly suggest a solid-state charge-transfer interaction in [Cr(bpy) 2 (NCS) 2 ]I 3 similar to that for I - in [Cr(dmb) 2 (NCS) 2 ]I.…”

“…For other structural examples in which there is evidence for a I 3 -/cation chargetransfer interaction, the reported interaction distances are between 3.70 and 4.11 Å. 15 The relative positioning and separation of the I 3and bpy ligand strongly suggest a solidstate charge-transfer interaction in [Cr(bpy) 2 (NCS) 2 ]I 3 similar to that for Iin [Cr(dmb) 2 (NCS) 2 ]I. Unfortunately, because of the interference from the strong, broad I 3spectral band we were not able to obtain the same sort of corroborating spectral data with I 3as was possible for I -.…”

Cation radical salts of ethylenedisulfanyl-bridged dimeric ethylenedithiotetrathiafulvalene with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (TCNQF4), PF6−, AsF6−and BF4−: synthesis, structure and conducting properties

“…The interplanar distance between two contiguous TCNQF 4 anions in one dimer is 3.10 A ˚, which is considerably shorter than what is expected for a van der Waals distance and also apparently shorter than what was observed in charge-transfer complexes with ferrocene (3.23 A ˚)17 and octamethylferrocenyl thioethers (3.16 A ˚). 18 The EDT-TTF units form dimeric structures in the column with an interplanar distance of 3.342( 12) A ˚. Two adjacent dimers in a column are linked by weak S … S interactions (S(6) … S(2 4c).…”

Radical Ion Salts Obtained from Substituted Ferrocene Cations and the Organic Acceptor TCNQ − Synthesis, Structure and Physical Properties

“…[19] Similar structural features are found in [Fe(C 5 H 5 )(C 5 H 4 CHϭCH-9-C 16 H 9 )][TCNQ] with pyrene acting as both a substituent on the cyclopentadienyl ring and overlapping with the TCNQ, which remains essentially neutral. [20] Of more interest, structurally, are compounds obtained with octamethylferrocenyl thioethers, [Fe(C 5 Me 4 SR) 2 ], R ϭ Me, tBu, and TCNQ or TCNQF 4 , [21] Our objective is to use these ferrocenes to build up a net of positive charges that will control the TCNQ stacking through electrostatic interactions. The size and orientation of the ferrocene cations can control the number of TCNQ units that will stack, thus inducing either the localization or the partial delocalization of electronic charges on the TCNQs.…”