Crystal Structures, and Electrical Conducting and Magnetic Properties in the Plate Crystals of (Ethylenedithiotetrathiafulvalenoquinone-1,3-dithiolemethide)2·MX4 (M=Fe, Ga, X=Br; M=Fe, X=C1) Salts

One-Dimensional CuBr42- Ion Array and CuBr3- Ion Chain Included in the π Conducting Framework Composed of Bis(methylthio)tetrathiafulvalenothioquinone-1,3-dithiocarbonatodithiolemethide Molecules

“…This signal can be readily assigned to be due to the Cu(II) d spins of CuBr 4 2- ions and {CuBr 3 - } n from the observed g -value . Presumably, the signal with a comparatively weak intensity due to the conducting π spins of 1 molecules is also very broad , and hidden inside the d signal. With lowering of the temperature from 300 K, the signal intensity increased and the increasing tendency continued until 3 K, the lowest temperature in this measurement.…”

Electrical Conducting and Magnetic Properties of (Ethylenedithiotetrathiafulvalenothioquinone-1,3-diselenolemethide)2·FeBr4 (GaBr4) Crystals with Two Different Interlayer Arrangements of Donor Molecules

“…On the other hand, the ESR spectra of 2 2 ·FeBr 4 ( I ) and 2 2 ·FeBr 4 ( II ) at 300 K showed only very broad doublet signals at g = 2.0610 (Δ H pp = 1002 Oe) and 2.0625 (939 Oe), respectively. , Of course, signals due to the conducting π electrons on the 2 -stacked columns as observed in 2 2 ·GaBr 4 ( I ) and 2 2 ·GaBr 4 ( II ) should also appear but will be hidden by the d signal because of weak intensity and broadness. With lowering the temperature from 300 K, the g and Δ H pp values of the d signals gradually increased, and the degree of increase became remarkable below ca.…”

“…The ESR spectra of 2 2 ·GaBr 4 ( I ) and 2 2 ·GaBr 4 ( II ) were measured at different temperatures between 3.6 and 300 K. These GaBr 4 - salts only involve spins due to the conducting π electrons on the 2 -stacked columns, since the GaBr 4 - ion is nonmagnetic. At 300 K, comparatively broad doublet signals were observed at g = 2.0055 (peak-to-peak width, Δ H pp = 110 Oe) for 2 2 ·GaBr 4 ( I ) and at g = 2.0031(158 Oe) for 2 2 ·GaBr 4 ( II ). , However, at 3.6 K, their signals became more sharp (Δ H pp = 30 Oe for 2 2 ·GaBr 4 ( I ) and Δ H pp = 29 Oe for 2 2 ·GaBr 4 ( II )), but the g -values were almost not changed (2.0066 for 2 2 ·GaBr 4 ( I ) and 2.0082 for 2 2 ·GaBr 4 ( II )). Now, the temperature dependences of g and Δ H pp values were investigated, and the results are shown in Figure .…”

“…Furthermore, as seen from Figure a, for 2 2 ·FeBr 4 ( I ) and 2 2 ·FeBr 4 ( II ) a sharp decrease in χ p occurs below 3.5 K, where antiferromagnetic ordering might begin to take place. The χ p − T behavior in the temperature range 5−300 K was analyzed by using the equation χ p = C /( T − θ) + χ π , where C is a Curie constant and θ a Weiss temperature due to the d spins of FeBr 4 - ions, and χ p is a temperature-independent χ p associated with the conducting π electrons on the 1 - or 2 -stacked columns. , The best fit to the observed data was obtained by choosing the following C , θ, and χ π values: C = 4.60 emu K mol -1 , θ = −5.3 K, and χ π = 0 emu mol -1 for 1 ·FeBr 4 ; C = 4.53 emu K mol -1 , θ = −7.3 K, and χ π = 8.0 × 10 -4 emu mol -1 for 2 2 ·FeBr 4 ( I ); C = 4.58 emu K mol -1 , θ = −6.7 K, and χ π = 8.0 × 10 -4 emu mol -1 for 2 2 ·FeBr 4 ( II ). All the C 's obtained are close to the value (4.68 emu K mol -1 ) calculated as an Fe(III) d spin entity with S = 5 / 2 and g = 2.069.…”

“…In our previous study, 3 and 4 gave only 1:1 CT salts with FeBr 4 - ion, whose room-temperature electrical conductivities were quite low . However, in the use of a carbonyl analogue of 4 , ethylenedithiotetrathiafulvalenoquinone-1,3-dithiolemethide ( 5 ), a highly conducting 2:1 CT salt with FeBr 4 - ion ( 5 2 ·FeBr 4 ) was obtained as plate and needle crystals, of which the needle crystal exhibited metallic conductivity above 170 K and very interestingly ferromagnetic interaction between the d spins of FeBr 4 - ions by participation of the conducting π electrons below ca. 15 K. Since very recent preliminary results indicate a possibility of ferromagnetic ordering below 1 K, indeed this needle crystal generates much expectation for the opening of a new research area of “molecular spintronics” based on the molecular π/d systems. −

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