Rose-Marie Lequan

A new strategy for building conducting Langmuir-Blodgett films

A new strategy for building conducting LB films is presented. The conducting behaviour is obtained by mixing in the same layer amphiphilic and semi-amphiphilic TCNQ derivatives. The optimum conductivity (6.9*10-3 S cm-1) is obtained for hybrid stacks of TCNQ in which the average electronic charge is -0.33.

A new class of conducting organo-metallic salts: TTF radical cation salts with metal halides

Abstract A new series of semi-conducting organo-metallic salts derived from tetrathiafulvalene (TTF) has been prepared by the electro-oxidation technique: (TTF) (MnCl3−)−0.75 ( σ RT ⋍ 15 Ω −1 cm −1 ), ( TTF ) ( MnCl 4 −− ) ⋍0.25 ( σ RT ⋍ 0.2 Ω −1 cm −1 ) and (TTF)(CoCl4−−)⋍0.25 ( σ RT ⋍ 0.2 Ω − cm − ). Preliminary X-ray work has shown that the first compound presents both regular TTF stacks and parallel inorganic chains. All of these compounds are strong paramagnets exhibiting antiferromagnetic interactions at low temperatures.

A new zwitterionic salt for non-linear optics: {4′-[methyl(diphenyl)phosphonio]biphenyl-4-yl}triphenylborate

The synthesis of {4′-[methyl(diphenyl)phosphonio]biphenyl-4-yl}triphenylborate (PBB) and 4′-(diphenylphosphino)biphenyl-4-yl(methyl)diphenylphosphonium hexafluorophosphate (PBP) is described. The properties of PBP and PBB are investigated by absorption and fluorescence spectroscopy. Diphenylphosphine is found to be a weaker donor group than the triphenylborate anion. The variation of dipole moment between excited and ground states as well as the hyperpolarisability coefficient, determined for PBB by solvatochromic methods, shows that this compound is promising for second-harmonic generation.

Conducteurs organiques : nouveaux complexes d'ions radicaux entre sels de diphosphonium et le tetracyanoquinodimethane (TCNQ)

Abstract Diphosphonium iodides form complexes with 7,7,8,8 Tetracyanoquinodimethane (TCNQ) of stoechiometry 1 : 4. These complexes are good conductors at room temperature.

A new class of electrically conducting organometallic salts with an unprecedented metallocene stack. Preparation and crystal structures of η5-cyclopentadienyl-η6-tri- and hexa-methylbenzeneiron(II) tetracyano-p-quinomethanides

Redox reactions between [(cp)FeAr]+I–(cp =η5-C5H5; Ar = 2,4,6-Me3C6H3 or C6Me6; readily prepared from the parent PF6 salts by exchange with Kl on anionic resin) and tetracyanoquinodimethane (TCNQ), afford electrically conducting, single crystals of the title compounds whose structures reveal, as a consequence of the difference in size of the two parallel planar ligands, one-dimensional segregated stacks of organometallic cations and TCNQ½– anions, a situation unique in metallocene complexes with electron acceptors.

Complexes organometalliques conducteurs derives de metallocenes et du tetracyanoquinodimethane

Abstract Organometallic conductors have been obtained from the reaction of substituted ferrocenic,arene-CpFe II and bis-areneiron(II) salts with TCNQ 0 and/or TCNQ − . The ionic complex of the bis(trimethylbenzene)iron(II) cation and TCNQ − shows a reverse electron transfer from TCNQ − to the cation, after thermal activation, yielding a semi-conductor species.

New Examples of Ternary Organic Conductors: Sulfonium Ion Radical Salts

Abstract Although several inorganic conductors are known as tertiary component materials,for instance chalcogenides,scarce are the conductors formed by the association of three organic entities.

Physical properties of ternary TCNQ compound Me3S+(I3−)13TCNQ−23

Abstract Single crystal X-ray diffraction, ESR and electrical conductance were studied to clarify both the magnetic and transport properties on a radical-anion salt of ternary compound, Me 3 S + ( I 3 − ) 1 3 TCNQ − 2 3 with respect to the role of the I3− sublattice. In the single crystal ESR study, the anisotropic behaviour and the temperature dependence of g factor and linewidth were measured down to around 100 K. From the anisotropy of the g-factor it was revealed that the ESR signal arises from the electrons of the TCNQ molecules and the spin susceptibility exhibited the abrupt decrease below 170 K(Tm), which is the sign of the metal-insulator transition. Ac electrical conductivity up to 3 MHz showed that the conductivity becomes strongly frequency dependent below Tm. Single crystal X-ray study clarified that relatively large value of the Tm is due to a strong coupling between the I3− chains and the TCNQ superstructure.

Nouveau conducteur organometallique:complexe du tetrathiofulvalene avec l'anion metallique trichloromanganate TTF (MnCl3)0,75

Abstract A new organometallic ion-radical salt has been prepared and studied. This complex is the first example of a series of conductors associating an organic chain and various metallic counter-anions.

Slipped versus zig-zag TCNQ stack upon steric control in conducting 1:4 diphosphonium-TCNQ salts

Abstract The structural and conducting properties of two 1:4 charge transfer disphosphonium-TCNQ salts, prepared by reaction of the corresponding iodides with TCNQ in hot acetonitrile, are compared. The diphosphonium-paraphenylene (DPPP 2+ salt resembles the classical analog 1:2 salt tetraphenylphosphonium-TCNQ, TPP(TCNQ) 2 , with slipped stacks and normal semiconducting behaviour. By contrast, the diphosphoniumcyclohexadiene (DPCH 2+ ) salts exhibits zig-zag TCNQ stacks and presents a phase transition at 205.5 K. This is described and discussed with special emphasis on a posiible analog between DPCH(TCNQ) 4 and N -methyl- N -ethyl-morpholinium MEM(TCNQ) 2 , which has recently been thoroughly studied.