Masagi Mizuno

Crystal structure and conduction property of the first quasi-one-dimensional conductor of tetrathiafulvalenium salt with mixed inorganic anions, (TTF)(ClO4)0.14±0.02(Cl)0.42±0.08

Abstract The first quasi-one-dimensional tetrathiafulvalenium conductor with mixed non-stoichiometric inorganic anions, (TTF)(ClO4)0.14±0.02(Cl)0.42±0.08, was crystallized electrochemically and found to have a structure of a tetragonal system with a = b = 11.213(2) A , c = 3.600(1) A , Z = 2 . Crystal structure was analyzed assuming the space group of P42/mnm. TTF radicals form stable segregated eclipsed stacks along the elongated c-axis but anions are fully disordered in the channels surrounded by the TTF stacks. The room temperature conductivity along the TTF stacks is 7–27 S/cm/. The conductor shows a sharp metal-insulator transition at 253±4 K and below this temperature it behaves as a one-dimensional variable range hopping (VRH) conductor down to 70 K. Another non-stoichiometric perchlorate of TTF, (TTF)(ClO4)0.62±0.02, was also obtained in polycrystalline form at the same electrochemical preparation and found to have a much lower powder conductivity (7 × 10−4 S/cm) which suggests a possible Peierls structure at room temperature for this compound.

X-ray absorption spectroscopic (XAS) study of nickel bisdithiolenes, (n-Bu4N)x[Ni(dmbit)2] (x = 2, 1, 0.29) and (n-Bu4N)[Ni(dmbbip)2]

Abstract X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) studies on the tetra( n -butyl)ammonium salt of [Ni(dmbit) 2 ] x − ( x = 2,1 and 0.29) and [Ni(dmbbip) 2 ] − have been performed in order to reveal the structural parameters of the [NiS 4 ] x− core along with the chemical state. The central nickel ions is confirmed to have coordination number four with square-planar geometry. The [NiS] bond distance in [Ni(dmbit) 2 ] − (2.154 A) is identical with that of [Ni(dmbbip) 2 ] − , but shorter than those of [Ni(dmbit) 2 ] 2− (2.178 A) and [Ni(dmbit) 2 ] 0.29− (2.165 A).

Preparation of thiophene-fused TTFs and their charge-transfer complexes

New symmetrical and asymmetrical tetrathiafulvalene (TTF) derivatives fused with diphenylthiophene have been successfully prepared via coupling method using neat P(OEt) 3 . Cyclic voltammogram of these compounds show two reversible oxidation potentials similar to TTF. Diphenylthiophene-fused bis(methylthio)tetrathiafulvalene forms an 1 : 1 charge-transfer salt with F 4 -TCNQ (tetrafluorotetracyano-p-quinomethane) which exhibits a four-probe electrical conductivity in 0.21 - 5.54 S/cm at 300 K.

Preparation and properties of mixed anion TTF conductors

Twenty one TTF conductors with mixed anions were prepared. The effect of disordered anion structure on conduction mechanism and on structural phase change are discussed.

VRH conduction in TTF salts with mixed anions

Abstract Structure and conduction properties are investigated among eleven 1D TTF conductors with mixed anions. Most of them have disordered anion lattice and obey Motts variable range hopping conduction. The role of disordered anion structure for the hopping behavior is evidenced by (TTF)(SCN) 0.47 (NO 3 ) 0.10 which has ordered anion lattice and obeys Arrhenius conduction. The effect of commensurate anion stoichiometry upon Peierls instability is suppressed by the anion mixing.

Preparation and Properties of Bis(Isotrithione)Benzoqunone, Bitbq and Its TTF Complex, TTF(bitbq)0.90

Abstract Tetrathiapentalenedithione has been combined with benzoquinone to obtain bis-isotrithionebenzoquinone(bitbq; 1,3,5,7-tetrathia-s-indacene-2,6-dithione-4,8-dione). The possible formation of complex with metal or organic donors has been examined. The cyclic voltammogram shows two sets of half-wave oxidation potentials separated to each other by 0.70 V. It can be reduced forming a salt with tetraethylammonium. It forms a non-stoichiometric complex with TTF, TTF(bitbq)0.90 by electrochemical oxidation. It was found to have a room temperature conductivity of (1.9−0.9)×10−3 S/cm along the elongated axis and behave as a semiconductor with variable temperature. It has lattice constants of a=7.23±0.02 A, b= 12.50±0.01 A, c= 10.91±0.01 A, α = 90.00°, β= 106.34±0.01°, γ = 90.00°, V= 946.05±0.29 A3 and belongs to a monoclinic lattice.

Theoretical estin[ations of third order optical nonlinearities for one dimensional metal chains

Abstract Third order optical nonlinearities of linear metal chains, which are formed in crystals and vacuum evaporated thin films of metal-dioxime complexes, are analyzed by using CNDO/SD-CI calculations. Intermolecular exicitonic states are revealed to act very important rolls to the excellent nonlinearities of the linear metal chains. The molecular hyperpolarizabilities γ increase with seventh power of the metal chain length.

THG properties of metal-dithiolene complexes

Since the large third-order optical nonlinearity of organic metal (alpha) -(BEDT-TTF)2I3 was reported by Huggard et al. in 1987, the nonlinear optical properties of organic metals have received great attention. New synthetic routes for metal-dithiolene complexes were developed in the last decade and several of the complexes which have a TTF-analogous structure proved to be good electrical conductors. THG activities of solutions of some of these metal-dithiolene complexes were measured by using a THG Maker fringe method. For example, the (Chi) (3) value of a 0.2 wt% DMF solution of Ni(dmbit)2TBA at 0.1 mm thickness was measured as 7.2 X 10-14 esu by using 1,319 nm Nd:YAG laser light. In this measurement the (Chi) (3) value of 2.8 X 10 -14 esu for the SiO2 glass was used as a reference. From this measurement a (Chi) (3) value as large as 3.6 X 10-11 esu is predicted for the neat compound.

Structure and conduction properties of new series of 1-D conducivors nith mixed inorganic anions, (TTF)(X)x(Cl)/sub y/-(X=ClO/sub 4/. BF/sub 4), SCN)-the effect of fhe anion disorder upon the conducting chains

Abstract A new series of 1-d TTF conductors of the non-stoichiometric composition of mixed inorganic anions was found to be isostructural to each other having a space group P42/mnm, tetragonal lattice and disordered anion structure with diverse stoichiometry. TTF radical forms stable 1-d conducting stacking column of the repeating distances of 3.595A–3.608A and shows d.c. conductivity of 7–72S/cm. All the conduction study with variable temperature showed metal-insulator transition around 250K and below this temperature it was found to be well fitted to the Motts 1-d variable range hopping model. The effect of the anion disorder and mixing upon the conducting chain is discussed in relation to the localization of the Bloch state perturbed by the random potentials of the anions.