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A new Ni(dmit)2-based organic magnetic charge-transfer (CT) salt, (m-PO-CONH-N-methylpyridinium)[Ni(dmit)2]·CH3CN, where PO = 2,2,5,5-Tetramethyl-3-pyrrolin-1-oxyl free radical and dmit = 2-Thioxo-1,3-dithiole-4,5-dithiolate, was obtained, the crystal structure and magnetic properties of which are reported. Magnetic susceptibility of the CT salt obeys a combination of 1D ferromagnetic (1DF) Heisenberg (J1DF = +0.26 K) and Singlet-Triplet (ST) models (JST = -51.2 K) with mean field (MF) approximation (JMF = -6.7 K), suggesting that spins on the PO radicals form 1D ferromagnetic chains and spins on the Ni(dmit)2 monoanions forms spin dimers at low temperature, the latter of which was also confirmed by band calculations.

A new BEDT-TTF-based salt with an organic free radical, α′-α′-(BEDT-TTF)2(PO-CONH-m-C6H4SO3)·H2O, has been prepared. The crystal structure consists of alternating donor and anion/water layers propagated along the c axis. The anisotropic radical anions form a head-to-head arrangement, which provides a permanent dipole moment. The effect on the nearest donor layer has been estimated to be 4.0 V. The salt has two crystallographically independent donor layers (A and B), one of which (A) is surrounded by the negative ends of the anion layer dipole whereas the B layers are bordered by the positive ends of the dipole. This structural feature suggests that layers A and B have different Fermi levels. To eliminate the imbalance, self-doping occurs whereby electron density is transferred from layer A to B. The temperature dependence of the magnetic susceptibility has 11.1% of extra Curie spins, from which a doping ratio of 12.7% has been estimated.

The synthesis, crystal structure and resistivity of a new semiconducting BEDT-TTF radical-cation salt containing the tris(oxalato)germanate(IV) anion is reported. BEDT-TTF 4 [Ge(C 2 O 4 ) 3 ].0.5dichloromethane crystallizes in the space group P 2 1 / c, a = 18.322(7), b = 11.919(4), c = 32.746(11) A, β = 105.797(5)°, V = 6881(4) A 3 , T = 295(1) K, Z = 4. Electrical resistivity measurements show that BEDT-TTF 4 [Ge(C 2 O 4 ) 3 ].0.5dichloromethane is a semiconductor with an activation energy of 0.224 eV and room temperature resistivity of 212 Ω cm.

In order to develop a kind of dual redox system with rechargeable battery property having potential high charge density, eight disulfide compounds carrying nitroxide radical have been prepared. Reflecting their multi-redox nature observed in their cyclic voltammetry data, they exhibit multi-step charge–discharge profiles with fairly large capacities over 200 Ah kg−1 for the first discharging processes. The Curie–Weiss type behaviors or 1D Heisenberg type profiles found for the respective radical compounds could be understandable by investigating the clarified crystal structures of four compounds (3, 4, 7, and 8) among them.

Several ferrocene derivatives (1–6) carrying nitroxide radical were prepared as dual redox compounds. They have distorted molecular structures and exhibit oxidation potentials based on both ferrocene and nitroxide groups except 4. The multi-step charge–discharge processes are discriminated for mono-substituted derivatives with the first discharge capacity up to 400 Ah kg−1 for imino-derivative 3, while relatively characterless profiles are observed for bis-substituted derivatives 4 and 6 with capacity over 300 Ah kg−1.

An anionic weak acceptor, 2-sulfo-1,4-benzoquinone, has provided a new BEDT-TTF (bis(ethylenedithio)tetrathiafulvalene) salt (BEDT-TTF)2(2-sulfo-1,4-benzoquinone)·H2O. Single crystal X-ray analysis indicates that the unit cell has two crystallographically independent donor layers, one of which has a β″-type packing motif and the other being disordered. Population analysis and SQUID magnetometry suggests that non-β″-layer has an α‴-type packing motif. The dual-layered salt shows metallic behavior with a metal–insulator transition at 90 K.

We have prepared new organic anionic acceptors, Br2XQNHCH2SO3− (2: X=Br, 3: X=BryCl1−y (y≈0.5), 4: X=Cl; Q=1,4-benzoquinone), that possess both an electron acceptor part (1,4-benzoquinone) and an anionic part (sulfonate). The reduction potentials of the PPh4 salts of 2, 3 and 4 are −0.45, −0.45 and −0.46 V (vs. SCE in CH3CN), respectively. The results indicate that they are weaker acceptors than chloranil (−0.13 V) and bromanil (−0.12 V). Each anionic acceptor (AA) provided two BEDT-TTF salts, β-(ET)5(AA)2·DCE·zH2O and λ-(ET)2(AA)·CH3OH (AA=2, 3, or 4; z=2: 0.97, 3: 0.83 and 4: 0.40). The structures and transport properties of the salts are reported.

Series of radical salts derived from a 2,4,6-triphenylpyridinium (TPP) carrying TEMPO-substituent and transition metal complexes were prepared by the anion exchange of the TPP–TEMPO tetrafluoroborate with [n-Bu4N][Ni(dmit)2], [n-Bu4N]2[Pd(dmit)2], [n-Bu4N]2[Pt(dmit)2], [n-Bu4N][Ni(mnt)2], or [n-Bu4N]2[Ni(mnt)2] to give crystals with different structural features. While weak antiferromagnetic interactions of the Curie–Weiss behavior of S = 1/2 spin are predominantly observed in the salts of Pd(dmit)2, Pt(dmit)2 and Ni(mnt)2, the magnetic behavior of 1:1 Ni(dmit)2 salt can be explained by the additional contribution from the spins on Ni(dmit)2 anions (χ − χTEMPO), obeying the 2D Heisenberg model. A couple of the oxidized salts, [TPP][Ni(dmit)2] as well as [TPP]2[Pd(dmit)2], exhibit semi-conducting properties with relatively high room temperature conductivities.

Structures and properties of three Mn(hfac)2 (hfac = hexafluoroacetylacetonate) complexes derived from two kinds of bis-TEMPO (2,2,6,6-tetramethylpiperdinyl-1-oxy)-substituted diamines are reported. In a complex derived from bis-TEMPO-substituted ethylenediamine, the unit is coordinated to the manganese atom to afford a spin system with weak antiferromagnetic intermolecular interactions, while apparent ligations of both TEMPO groups to the metal atom are observed in a couple of Mn(hfac)2 complexes derived from bis-TEMPO-substituted piperadine to result in spin systems with fairly large antiferromagnetic interactions.

We have prepared a novel organic anionic weak acceptor, 2-aminomethylsulfo-3,5,6-trichloro-1,4-benzoquinone (1), as a PPh4 salt. Cyclic voltammetry indicates that its reduction potential is 0.53 V lower than that of chloranil. Electrocrystallisation with BEDT-TTF gave two salts, β - β -(BEDT-TTF)2(1)⋅0.5H2O (2) and β ″ - (BEDT-TTF)2(1)⋅CH3OH (3). Their crystal structures and physical properties are reported.

Series of organic radical compounds with trans -azobenzene chromophore have been prepared to see the photo-induced isomerizations to the corresponding cis -azobenzenes and the possible changes of intermolecular magnetic interactions based on the isomerizations. Although the cis -isomers with p -nitro- or p -dimethylamino-substituent on one side and TEMPO-attached long alkoxy group on the other side could not be isolated as stable solids, the cis -isomers of unsubstituted derivatives at 4-position and with a TEMPO group at 4′-position have successfully been isolated as relatively stable solid materials showing apparent changes of intermolecular magnetic interactions. A couple of Mn(hfac) 2 complexes derived from isomeric TEMPO-substituted esters were found to be reluctant to the photo-isomerization upon irradiation.

Several radical salts derived from a TEMPO-substituted 2,4,6-triphenyl pyridinium have been prepared by replacing the fluoroborate anion with an anionic metal-complex such as Ni(dmit) 2 , Pd(dmit) 2 or Ni(mnt) 2 and their structures and physical properties were investigated. The oxidized salts of the Ni(dmit) 2 as well as Pd(dmit) 2 complexes show semi-conducting properties with relatively high conductivities and low activation energies.

A new BEDT-TTF-based salt with an organic free radical TEMPO has been prepared. The salt consists of alternate layers of conducting and magnetic sheets, between which are short S(BEDT-TTF) …O(TEMPO) contacts. The magnetic susceptibility is well modelled by the combination of a 2D Heisenberg and a Curie–Weiss model with J = − 89 K and θ = + 0.05 K .

We have prepared eight TEMPO-containing anions TEMPO – A – CO – ( n - ) C 6 H 4 S O 3 - (n = o, m, p for A = NH (N1, N2, N3), n = o, p for A = NCH3 (M1, M3), and n = o, m, p for A = O (O1, O2, O3)) as PPh4 salts. Metathesis of their salts with (TTF)3(BF4)2 gave their TTF salts. Electrocrystallization of BEDT-TTF with PPh4 · M1 yielded the α-(BEDT-TTF)3(M1)2 · 8H2O salt. We report their crystal structures, electrical resistivities, and magnetic properties. The relation between crystal structures and physical properties are discussed.

Series of monoradicals and biradicals having an aromatic core on one hand and long alkyl groups on the other hand have been prepared. It was found from their magnetic data that the biradical compounds having aromatic cores (azoxy, or azo) and long alkyl groups with TEMPO radicals at their ends showed fairly large antiferromagnetic interactions ( J = −34, −39 K) being well expressed by ST model, while only weak antiferromagnetic interactions were observed in the corresponding PROXYL derivatives together with the corresponding monoradicals. The change of intermolecular magnetic interactions based on the structural change from trans - to cis -isomer by irradiation was found to be possible in a couple of azobenzene derivatives with an aminoxyl radical.

In order to investigate molecular conductors containing magnetic anions, πd-interactions Jπd and dd-interactions Jd, have been estimated from the overlap of molecular orbitals by using the relation J = −2t2/U. In the present paper this method is applied to a new antiferromagnetic superconductor (BDA-TTP)2FeCl4, a semiconducting ferrimagnet (EDT-TTF-VO)2FeBr4, and a β′-type semiconductor (BEDT-TTF)3(MnCl4)2. The dd interaction of (BDA-TTP)2FeCl4 is as large as λ-(BETS)2FeCl4, guaranteeing the relatively high TN. The small Jπd of this compound is related to the steric effect of the outer trimethylene groups of the donor. The observed ferrimagnetism in (EDT-TTF-VO)2FeBr4 is related to the localization of the π-electrons associated with the charge order, as well as the fairy large πd-interactions bridging different anions. (BEDT-TTF)3(MnCl4)2 is a characteristic compound due to the extraordinarily large πd-interactions to the donors incorporated in the anion layer.

Five TEMPO-containing anions TEMPO - CONA ( CH 2 ) n SO 3 - (H0−, A = H, n = 0; H1−, A = H, n = 1; H2−, A = H, n = 2; H3−, A = H, n = 3; M2−, A = CH3, n = 2) have been prepared as PPh4 salts. So far three TTF salts ((TTF)(H1) · 2H2O, (TTF)(H2) · H2O, and (TTF)(M2) · 0.50H2O), one TMTSF salt ((TMTSF)(H1) · 2H2O · PhCl), and one BEDT-TTF salt (α-(BEDT-TTF)5(H1)2 · 6H2O) have been obtained. Their crystal structures, electrical resistivities, and magnetic properties are reported.

New organic functional anions that includes the ferrocenyl group, CpFeCp-CONHCH 2 SO 3 − and Fe(Cp-CONHCH 2 SO 3 − ) 2 , are prepared as tetraphenylphosphonium (PPh4) salts. They reacted with (TTF) 3 (BF 4 ) 2 to give TTF monocation salts. The X-ray analyses indicate that for all salts TTF forms a dimer which is separated by the relatively larger anions. The oxidation reaction of (PPh 4 )(CpFeCp-CONHCH 2 SO 3 ) with I 2 gave the Zwitter-ion, CpFe + Cp-CONHCH 2 SO 3 − , which shows a Curie-Weiss behavior ( C = 0.800 emu·K/mol, θ = −1.13 K) with weak antiferromagnetic interaction. This magnetic moment is found to be attributed to the ferrocenyl radical.

We report here four novel purely organic magnetic conductors containing common electron donors together with an organic anion including an organic free radical, (TTF)(TEMPO-NHCOCH 2 SO 3 )·0.5H 2 O ( 1 ), (TMTSF)(TEMPO-NHCOCH 2 SO 3 )·2H 2 O ( 2 ), (BEDT-TTF) 3 (TEMPO-NHCOCH 2 SO 3 ) 2 ·2H 2 O ( 3 ), and α-(BEDT-TTF) 3 (TEMPO-NHCOCH 2 SO 3 ) 2 ·6H 2 O ( 4 ). The TTF complex was prepared by metathesis of (TTF) 3 (BF 4 ) 2 and the PPh 4 salt of the anion ( 5 ). The other complexes were obtained by electrocrystallization of the corresponding donors with the salt 5 as an electrolyte. Crystal structures of 2–4 have been solved. The salts 1 and 2 show relatively high resistivities (>10 7 and 5 × 10 3 Ω·cm), whilst the BEDT-TTF salts 3 and 4 have rather low room temperature resistivities (1.2 and 5.1 Ω·cm) with small activation energies (0.041 and 0.050 eV). The magnetic behavior of complex 1 obeys the Curie-Weiss law ( C = 0.379 emu·K/mol and θ = −3.29 K) and those of the other complexes obey the 1-D Heisenberg model ( C / J = 0.366/−0.32 for 2 , 0.373/−0.81 for 3 , and 0.380 emu·K·mol −1 /+0.42 K for 4 ). The relationships between the crystal structures and the physical properties are discussed.

The TaF 6 and FeBr 4 salts of BDA-TTP [2,5-bis(1,3-dithian-2-ylidene)-l,3,4,6-tetrathiapentalene] have been prepared and characterized as β-(BDA-TIP) 2 TaF 6 and β-(BDA-TIP) 2 FeBr 4 , respectively. The crystal structure of β-(BDA-TTP) 2 TaF 6 is isostructural to those of the ambient-pressure superconductors β-(BDA-TTP) 2 X (X = SbF 6 , AsF 6 and PF 6 ), but this salt undergoes an Ml (metal-to-insulator) transition instead of a superconducting transition at ambient pressure. The β-(BDA-TTP) 2 FeBr 4 salt, which is isomorphous to the superconductors β-(BDA-TTP) 2 MCl 4 (M = Fe and Ga) under applied pressures, exhibits a phase transition near 170 K and antiferromagnetic ordering with the Neel temperature (T N ) of about 9.5 K at ambient pressure.

We report the structures and physical properties of new β′-(BEDT-TTF)[Fe(oxalate)]·G salts where A = HO, G = PhCl; A = Rb G = Pyridine. The structure of the PhCl salt is isomorphous with β′-(BEDT-TTF)[(HO)M(oxalate)] with other guest molecules. PhCl is ordered in die hexagonal pockets formed by the [(HO)Fe(oxalate)] layer. The electrical conductivity is metallic down to 100 K, below which the resistivity increases with decreasing temperature. The specific conductivity at room temperature is about 10 S/cm. We also report the salt β′-(BEDT-TTF) [RbFe(oxalate)]·Pyridine where Rb replaces HO. The electrical resistivity shows metallic behavior down to 100 K. and turns up gradually to a maximum at 65 K below which the system re-enters the metallic state down to liquid helium temperature. Neither salt shows superconductivity down to 2 K. In addition, other new β′-(BEDT-TTF)[(HO)M(oxalate) ]·salts with M = Cr, Ga, Fe; G = CHCl , CHClBr, CHBr are also reported. © 2005 Elsevier B.V. All rights reserved.

A novel ferrocene-containing dianion, Fe(C5H4–CH(CH3)NHCOCH2SO3–)2 (1), has been prepared. The oxidation potential of the PPh4 salt is + 0.35 V (vs. SCE in PhCN), indicating that it is a stronger donor than TTF (tetrathiafulvalene) by + 0.03 V. The dianion provided a TTF salt, the structure and physical properties of which are reported.

Several anthracene derivatives with stable radical substituents have been prepared and their magnetic properties have been investigated together with those of some of the dimers available by photo-dimerization reaction. While weak magnetic interactions with Curie–Weiss behavior have been observed in most derivatives prepared, antiferromagnetic behavior being based on an S–T model has been found in the spins of TEMPO-substituted N-methylcarboxyamidoanthracene derivative 1c. The magnetic property of Mn(hfac)2 complex derived from 4-amino-TEMPO-substituted 9-methylanthracene (1d) is also described.

In recent years, concern has been raised about the charge fluctuation of the superconducting transition in the loosely dimerized molecular conductors. Not only the observation of the charge fluctuation is of considerably important but also the understanding of the mechanism of the fluctuation. We have observed degree of charge fluctuation of several β''-type ET salts. The β''-type ET salt is one of the best model compounds because the direction of the largest inter-site Coulomb interaction is perpendicular to that of the largest transfer integral. This structural property allows us to examine the role of inter-site Coulomb interaction from the viewpoint of the inter-molecular distance. The difference in the molecular charges between the charge rich site and the charge poor sites, Δρ, is correlated with the conducting behavior; the superconducting materials have the small but finite Δρ, whereas Δρ of the insulating (metallic) materials is large (almost zero). After the analysis of the configuration in the inter-molecular distances, we have found that the degree of fluctuation, Δρ, is attributed to the number of the most stable charge distribution(s), NS, and the number of the energy levels of the allowed charge distribution, NA. The superconducting materials belong to the condition of N ≥2 and N ge;2. Indeed, this condition contributes to the fluctuation of the molecular charges. © 2010 Elsevier B.V. All rights reserved.

BEDT-TTF salts have been widely studied because of their ability to combine various physical properties in the same lattice. The series of salts containing tris(oxalato)metallate anions has been widely studied and has given rise to paramagnetism, ferromagnetism, superconductivity, semiconductivity, conductivity and proton conductivity. However, one property that has not been exploited fully in this family of materials is chirality.

To study the anisotropic Josephson-vortex dynamics in the d-wave superconductors, the interplane resistance has been measured on layered organic superconductors κ ‐ ( ET ) 2 Cu ( NCS ) 2 and β ‐ ( BDA ‐ TTP ) 2 SbF 6 under magnetic fields precisely parallel to the conducting planes. For κ ‐ ( ET ) 2 Cu ( NCS ) 2 , in-plane angular dependence of the Josephson-vortex flow resistance is mainly described by the fourfold symmetry and dip structures appear when the magnetic field is applied parallel to the b- and c-axes. The obtained results have a relation to the d-wave superconducting gap symmetry. However, the absence of in-plane fourfold anisotropy was found for β ‐ ( BDA ‐ TTP ) 2 SbF 6 . The different anisotropic behavior is discussed in terms of the interlayer coupling strength.

The heat capacity of the title compound has been measured below room temperature by adiabatic calorimetry. A structural phase transition and a glass transition, both probably related to the intramolecular crankshaft motion, were detected at 273 K and 250 K, respectively. The degree of charge transfer (CT) was determined from IR spectroscopy as approximately 0.2e−. Since the central CC moiety of the stilbene molecule has a significant density in the HOMO, the observation of the phase and glass transitions means that the part involved in the CT interaction reorients itself in the crystal lattice above the glass transition temperature.

Temperature–pressure phase diagram of the 2-D organic conductor, κ-(DHDA-TTP)2SbF6 (DHDA-TTP = 2-(1,3-dithiolan-2-ylidene)-5-(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene) is presented. This phase diagram exhibits a pressure boundary between insulator and Fermi liquid (FL). This boundary is considered as a critical pressure of quantum fluctuation between probable charge ordering and FL ground states. In the vicinity of the specific pressure, divergence of the prefactor A in ρ = ρ0 + AT2, is observed, where ρ is the in-plane resistivity and T is the temperature. Following the similar phase diagram to κ-(MeDH-TTP)2AsF6 by Yasuzuka et al., this is the second example in the two-dimensional 1/4-filled organic conductors, showing the temperature–pressure phase diagram of quantum critical behavior. It is remarkable that this kind of divergence of A at certain critical point is rather general phenomena at least in these 1/4-filled 2-D organic conductors, in contrast to the other 1/2-filled κ-type organic conductors, which show Kanoda's phase diagram with Mott insulator and superconductor.

A glass transition due to the freezing of intramolecular motion is reported for κ-(ET) 2 Cu[N(CN) 2 ]Br around 105 K on the basis of heat capacity spectroscopy utilizing chopped-light a.c. calorimetry on a single crystal around 10 Hz. The glass transition temperature in the daily time scale (ca. 10 3 s), well corresponds to the temperature below which the physical properties including the superconducting transition temperature depends on the thermal history (e.g. cooling rate or annealing). The history dependence is reasonably resolved by taking into account the glass transition.

Several organic radical compounds based on TEMPO radical with cholesterol and benzylideneamine cores ( 3a – c ) were prepared. The radical compounds were found to freeze into glassy state when cooled from their isotropic liquid state and characteristic heat-responsive magnetic properties were observed in the radicals due to the phase transitions.

A series of aminoxyl radicals (nitronyl nitroxide or TEMPO) bearing biphenylcarbonitrile as a mesogenic core ( 2a–2c and 3a–3c ) was prepared. Among them, unusual magnetic transition from the original Curie–Weiss phase to another magnetic phase well expressed by a singlet–triplet model was found in the 4′-undecyloxy-4-biphenylcarbonitrile derivative with oxocarbonyl-TEMPO through the thermal transition.

The reactions of TEMPO derivatives having a benzylideneamine unit with Cu(hfac)2 revealed unexpected formation of a complex consisting of 4-amino-TEMPO and Cu(hfac)2 and its crystal structure and magnetic properties showed marked difference from those of the corresponding Mn(hfac)2 complex and a complex derived from bis-TEMPO-substituted-ethylenediamine

The high frequency (f=70 GHz) magneto-optical response of β-ET 4 [(H 3 O)M(C 2 O 4 ) 3 ].S, where M=Fe 3+ , S=C 6 H 5 CN and C 6 H 5 NO 2 , has been investigated in the temperature range 1.4 K < T < 120 K. The angle dependence of the EPR spectra and the anisotropy of the g-factors for the two materials are presented.

The title compounds containing diamagnetic Ga are superconductors. The nitrobenzene salt shows a broad metal-semiconductor transition at 160 K but becomes superconductor below 7.5 K. The Meissner volume of a powder sample at 1.8 K is estimated at 31%. The pyridine salt also has a broad upturn in resistance at 130 K, a re-entrant metallic phase below 60 K, and a resistance loss below 1.5 K. The loss vanishes with applying magnetic field, suggesting that it is also superconductor.

Transport measurements have been carried out on single crystals of the charge transfer salt β-(BEDT-TTF) 4 [(H 3 O)Ga 3+ (C 2 O 4 ) 3 ]. C 6 H 5 NO 2 , using magnetic fields of up to 33 T and temperatures down to 0.55 K. The material is found to be superconducting with T c 7.5 K and an in-plane critical field B c2 ≥ 33 T, and to exhibit Shubnikov-de Haas (SdH) oscillations. The temperature and angle dependence of the Shubnikov-de Haas oscillations and the upper critical field are reported, allowing information about the anisotropy of the upper critical field, effective mass m*, and the Fermi-surface (FS) of the material to be deduced.

Charge transfer salts with stoichiometry β″-(BEDT-TTF) [M(CO),](18-crown-6 ether)(9HO), where M= Cr, Ga or Fe and x= 2 or 3 are reported. Their structures suggest that proton migration is possible. Variable temperature resistivity measurements on the Cr salt show metallic behaviour down to 180K. Magnetic susceptibility of the Cr salt is paramagnetic down to 1.8 K. Preliminary impedance measurements suggest that the proton conductivities of the Cr and Ga salts are the order of 10 S cm at 300 K. © 2003 Elsevier Science B.V. All rights reserved.

Heat capacities of κ-(BEDT-TTF) 2 Cu[N(CN) 2 ]X (X= Br and Cl) and deuterated salts were measured by chopped light are calorimetry. A glass transition due to freezing of the conformation of the ethylene moiety in the BEDT TTF molecule was deteeted around 100 K at 0.24 - 16 Hz on each salt. The glass transition temperature (ca. 80 K) at daily time scale (ca. 1 mHz) we corresponds to the temperature at which the ccoling rate or annealing sigmficantly alfect the physical properties of the superconducting transition temperature and Meissner volume on κ-(BEDT-TTF) 2 Cu(N(CN) 2 ]Br and κ-(BEDT-TTF-d 8 ) 2 Cu[N(CN) 2 ]Br.

The preparation and characterization of new organic radical anions TEMPO-NHSO 3 . (tsfa) and TEMPO-OSO 3 - (tosu), which consist of the organic stable radical (TEMPO) and the anionic functional group (-NHSO 3 - or -OSO 3 - ), has been investigated. The molecular and crystal structures of bis(triphenylphosphoranylidene)ammonium.tsfa determined by X-ray analysis indicate that tsfa exists as a monovalent anion. Black powders of the TTF.tsfa and TTF.tosu salts were obtained, in each of which the donor to anion ratio is found to be 1 : 1 by elemental analysis. TTF.tsfa shows a weak antiferromagnetic interaction with C = 0.360 emu K mol -1 and θ = -0.52 K.

The λ-type BETS alloys (BETS=bis(ethylenedithio)tetrathiafulvalene), λ-BETS2FexGa1 − xCl4 exhibited an unprecedented superconductor-to-insulator (SC-I) transition around x = 0.43 at ambient pressure. The large susceptibility drop at Tc and its recovery at tsc-i clearly show this SC-I transition reflects an intrinsic property of the crystals. The anisotropic field dependence of magnetization at 2 K indicated the insulating ground state to be antiferromagnetic. λ-BET2FexGa1 − xCl4 undergoes a MI transition at x>xc1 (≈0.5), SC transition at x