Columnar stacking materials based on donor/acceptor complexes of tetrathiofulvalene/coinage-metal metallocycles

Columnar stacking materials based on donor/acceptor complexes of tetrathiofulvalene/coinage-metal metallocycles Rossana Galassi1, Oumarou Camille Simon1, Vladimir Nesterov2, Alceo Macchioni3, Cristiano Zuccaccia3, Mohammad A. Omary2 Tetrathiofulvalene and dibenzotetrathiofulvalene, TTF and DBTTF respectively, are strong one- or two-electron donors,[1] whereas a class of cyclic trinuclear coinage complexes, in which the bridging ligand is a 3,5-pyrazolate disubstituted with electron-withdrawing groups, are known to be electron-acceptors.[2] Recently, we have proved the electrophilic behavior of the [Ag(3,5-(NO2)2pz)]3 cyclotrimer towards small volatile organic or inorganic molecules (e.g., NH3, acetone, acetonitrile, pyridine, and dimethylsulfide). This behavior was compared to that of [Ag(3,5-(CF3)2pz)]3 and rationalized in terms of inter-trimer bonding energies.[3] Moreover, electron-rich trinuclear metallocycles were observed to react with electron-poor organic counterparts, such as TCNQ (7,7’,8,8’-tetracyanoquinodimethane). In order to obtain new classes of materials with potentially-interesting conductive properties, reactions between reactants having these opposite donor/acceptor characteristics have been carried out and reported herein. By mixing solutions of the corresponding Au, Ag or Cu trinuclear derivatives and TTF or DBTTF, the formation of the relative adducts was observed. The compounds were characterized by elemental analysis, IR, ESI-MS, and 1H NMR spectroscopy. Moreover, the X ray diffraction structure determination was performed on suitable crystals of the [Cu(3,5-(CF3)2pz)]3 . DBTTF complex. This compound is mostly stable both in the solid state and in solution as highlighted by 1H and 19F NMR, and by UV/visible spectroscopies. The [Ag(3,5-(CF3)2pz)]3 . DBTTF and [Au(3,5-(CF3)2pz)]3 . DBTTF analogs have been isolated and their characterizations suggest similar structures in the solid state, but less stability in solution. The [Ag(3,5-(NO2)2pz)]3 metallocycle shows a stronger interaction with both TTF and DBTTF, readily attaining highly-colored precipitates, albeit with too low solubility for single-crystal XRD analysis. Leave one line blank [1] J. Ferrari et al., J. Am. Chem. Soc., 1973, 95 (3), pp 948–949; T.J. Emge et al., Molecular Crystals and Liquid Crystals, 1982, 87 (1-2), pp 137-161 [2] M. A. Omary et al., J. Am. Chem. Soc., 2008, (130), pp 1669–949 [3] R. Galassi et al., Inorg. Chem., 2013, 52, pp 14124 -14137