Philippe Molinié

Novel Infinite Three‐Dimensional Networks with Highly Conjugated Polynitrile Ligands: Syntheses, Crystal Structures, and Magnetic Properties of [Cu{C[C(CN)2]3}(H2O)2]n and [Cu{C[C(CN)2]3}(en)]n (en=NH2CH2CH2NH2)

An unprecedented coordination mode for the highly conjugated cyanocarbanion [C{C(CN)2}3]2− (1) is observed in the title complexes. This ligand employs four of its six CN groups in a μ4-η4 bridging mode to form two unique three-dimensional polymers.

Interplay of Structural Flexibility and Crystal Packing in a Series of Paramagnetic Cyclopentadienyl/Dithiolene Mo and W Complexes: Evidence for Molecular Spin Ladders

The structural flexibility of [Cp2M(dithiolene)] complexes (M=Mo, W; dithiolene=dmit2−, dmid2−, dsit2−; the [CpMo(dmid)] complex is depicted on the right) is manifested in various folding angles of the MS2C2 metallacycle in a series of charge-transfer salts with TCNQF4. The evolution of the electronic structures with the folding angle induces different geometries for the dimeric [{Cp2M(dithiolene)+.}2] entities. The organization of these entities in the solid state reveals one-dimensional intermolecular interactions, as confirmed by the magnetic behavior of these salts, which are characteristic of a spin chain or a rare spin ladder motif (shown on the right).

Cyano-Halogen Interactions in [EDT-TTF-I]2[Ni(mnt)2] and [EDT-TTF-I2]2[Ni(mnt)2] and Geometrical Evolutions within Mixed-Valence or Fully Oxidized TTF Dyads

The structure of the iodo-substituted tetrathiafulvalene derivative EDT-TTF-I is described, with neutral molecules associated into inversion-centred dyads; no short intermolecular I···I contacts are observed. Electrocrystallisation of EDT-TTF-I (1) or EDT-TTF-I2 (2) in the presence of [nBu4N][Ni(mnt)2] afforded 2:1 salts, formulated as [1]2[Ni(mnt)2] and [2]2[Ni(mnt)2]. In both salts the organic donor molecules 1 or 2 are associated into inversion-centred dyads, connected to the [Ni(mnt)2] species through a short, directional CN···I interaction. The dyads alternate with the nickel dithiolene complex into mixed ...DDADDADDA... stacks. Comparisons in both salts of intramolecular bond lengths, intra-dyad overlap modes, and magnetic susceptibilities, indicate a full charge-transfer in [1]2[Ni(mnt)2], formulated as [1]22+[Ni(mnt)2]2−, while a mixed-valence state is observed in [2]2+·[Ni(mnt)2]−·. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

MAGNETIC AND CONDUCTIVITY STUDIES OF POLY(VINYLENE DISULFIDE)

We report the results of magnetic [electron‐spin resonance (ESR) and susceptibility] and conductivity measurements on a new type of semiconducting polymer: poly(vinylene disulfide)–(S—CH=CH—S)n synthesized from (E)‐1,2 dithiocyanatoethene. ESR spectra of pristine and protonic acid doped samples have four g factor values which can be explained by the nonplanar structure of the polymer. Decrease in paramagnetism and enhancement of the spin density by doping are observed to be in close relation with the increase of the conductivity. A conduction mechanism assuming direct protonation of the polymer backbone is proposed to explain the behavior of these polymers upon chemical doping by protonic acid.

RADICAL CATION-RADICAL ANION SALTS : MOLYBDENUM COMPLEXES CONTAINING THE TCNQ.- OR TCNE.- RADICAL ANIONS. X-RAY CRYSTAL STRUCTURE OF MO(ET2NCS2)4(TCNQ )

Abstract The reactions between the molybdenum(IV) complexes [Mo(dtc) 4 ] 1 (dtc = Et 2 NCS 2 for 1a and Me 2 NCS 2 for 1b ) and TCNQ produced the 1 : 1 derivatives [Mo(dtc) 4 ](TCNQ) 2. Subsequent reaction of 2 with TCNQ gave the 1 : 2 complexes 3 [Mo(dtc) 4 ](TCNQ) 2 . Complexes 1 reacted with TCNE under nitrogen to give the 1 : 1 compounds [Mo(dtc) 4 ](TCNE) 4 while under ambient conditions the pentacyanopropenide derivatives [Mo(dtc) 4 ](NC) 2 CC(CN)C(CN) 2 ] 5 were obtained. In solution, cyclic voltammetry and ESR studies revealed the presence for all types of complexes of the molybdenum(V) radical cation [Mo(dtc) 4 ] •− which is associated with the radical anion TCNX •− in 2 (X = Q) and 4 (X = E) and with a 1:1 mixture of neutral and anionic TCNQ species in 3 . Complex 2a has been studied by single crystal X-ray diffraction. The crystal structure consists of monomeric TCNQ •− radical anions and [Mo(dtc) 4 ] •+ cations with a triangular dodecahedral arrangement of S atoms and a point group symmetry which is approximately D 2 d .

Polymeric networks of copper(II) ions linked by a bridging polynitrile ligand

Synthesis, crystal structure and magnetic properties of [Cu{C[C(CN) 2 ] 3 }(en) 2 ] n , which arises from reaction of Cu(II) with the highly conjugated polynitrile C 10 N 6 2 ligand ( C 10 N 6 2 = [C{C(CN) 2 } 3 ] 2. ) in presence of ethylenediamine (an = NH 2 CH 2 CH 2 NH 2 ). are reported. This compound presents a polymeric structure of pseudo-octahedral copper(II) ions bridged by the polynitrile unit C 10 N 6 2 . The magnetic susceptibility data in the 5-300 K range can be analysed by a Curie law with C = 0.43 cm 3 . K.mol -1 .

Organic and polymer-based light-emitting diodes

Publisher Summary Considerable research efforts in recent years have been dedicated to the development of electroluminescent polymers and organic materials for use in light-emitting diodes (LEDs). The efforts were stimulated by the potential applications of these devices in the electronics industry. The main advantages of such LEDs over inorganic ones are that they are lightweight and have a large active area and flexibility. These factors favor their use not only in display technology but in other fields as well. This chapter discusses organic and polymer-based LEDs. The study of transport mechanisms in diodes has progressed significantly, mainly in the polymer field. Although many concepts used in classical semiconductors have been found to be valid for organic or polymer-based diodes, some new ideas have been proposed to satisfactorily explain the transport of carriers in the devices. Particularly interesting results have been obtained by intensive studies on the role of the contact between the polymer (organic material) and the metal electrode in the injection mechanisms of charge carriers.

Elaboration and characterization of various carbon nanostructures

Abstract Evaporation of carbon in the presence of helium produces a large variety of carbon cage molecules with quasi-spherical (fullerenes), tubular (carbon nanotubes) and polyhedral (graphitic nanoparticles) morphologies. Co-evaporation of carbon with another element (or mixture of elements) of the periodic table in the presence of helium yields interesting modifications of those structures. The nanotubes can be single- or multi-walled depending on the nature of the additional element and on the experimental conditions. In some caes, the nanotubes as well as the polyhedral particles can be filled with cylindrical single crystals of the element, while in some other cases an encapsulated carbide is formed. Another way of modifying carbon nanostructures is the substitution of B and N into the carbon network. These variations lead to changes in the physical properties of the nanostructures.

Structural and electrical properties of bis(ethylenedithio)tetrathiafulvalenium hydrogen fumarate (2/1): a BEDT-TTF mixed-valency salt with a hydrogen-bonding organic anion

Electro-oxidation of BEDT-TTF in the presence of tetrabutylammonium hydrogen fumarate affords the salt (BEDT-TTF) 2 [(E)-HO 2 C-CH=CH-CO 2 ], in which the BEDT-TTF units adopt a β-type packing and the organic anions form infinite chains by hydrogen-bonding; this salt is a semiconductor and its room-temperature conductivity is ca. 3 S cm –1 .

Determination of charge transfer in molybdenum complexes of 7,7,8,8-tetracyano-p-quinodimethane with vibrational spectroscopy

Abstract The influence of charge transfer on the vibrational lines of three new molybdenum TCNQ complexes [MoO(dtc)3](TCNQ) 1a, [Mo(dtc)4](TCNQ) 2a, and [Mo(dtc)4](TCNQ)2 3a is reported (dtc=Et2NCS2). It is shown that Raman scattering is able to probe the charge state of TCNQ entities in these complexes. Infrared spectra are discussed and compared to Raman spectra. Electronic polarization of the TCNQ moieties and reduction of TCNQ° in TCNQ•− is found for all complexes. The estimated charge transferred when reduction occurs is one electron onto the TCNQ molecule whereas it is about 0.2–0.3 electron onto nitrile groups. The formation of monomers and dimers of TCNQ in these complexes is discussed in relation with specific Raman lines found in reference compounds such as TCNQ salts of alkali. These new Raman data suggest to us that TCNQ moieties form mainly dimers and monomers in complexes 1a and 2a, respectively.