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The conditions that allowed for the first time the growth of (Per)2[Pd(mnt)2] crystals by electrocrystallisation are described. The electrocrystallisation is limited by close proximity of the oxidation potentials of the perylene donor and [Pd(mnt)2]- anion. Depending on the experimental conditions different morphologies can be obtained. (Per)2[Pd(mnt)2] crystals were found to be mainly of the β-polymorph with properties comparable to the Cu, Ni and Pt previously described. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The charge transfer salt based on the organic donor dithiophene-tetrathiafulvalene and palladium bis-maleonitrile-dithiolate, (DT-TTF)2[Pd(mnt)2], was obtained as single crystal by electrocrystallisation in dichloromethane. The crystal structure is different from the analogues previously described with other metals (Au, Cu, Ni and Pt) but of the same type as (TTDM-TTF)2[Au(mnt)2]. However in this DT-TTF salt the Pd complex is dianionic, being the donor molecules fully oxidised and the compound should then be formulated as (DT-TTF+)2[Pd(mnt)2]2-. This compound has properties of a quasi-one-dimensional semiconductor with sRT∼ 6 × 10-2 Scm-1 and Ea∼0.172 eV (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The preparation and characterization of new salts based on the dissymmetrical TTF derivative CNB-EDT-TTF (cyanobenzene-ethylenedithio-tetrathiafulvalene) and BF4− anions, are reported. Depending on the electrocrystallization conditions salts with different stoichiometries, (CNB-EDT-TTF)BF4 and β”-(CNB-EDT-TTF)4BF4, can be obtained. The 1:1 salt is an electrical insulator isostructural to the ClO4 analogue previously described. The 4:1 salt is a new member of the family of 2D metals of this donor with different small anions X, (CNB-EDT-TTF)4X, characterized by a bilayer arrangement of the donors and it was obtained in a monoclinic polymorph with a β”-type donor packing pattern. The small anions in this compound are severely disordered between the donor bilayers, which present slightly larger lattice parameters than the isostructural ClO4 analogue. Both electrical conductivity and thermoelectric power measurements in single crystals denote metallic properties as predicted by electronic band structure calculations. As a consequence of the anion disorder the metallic regime of the electrical conductivity denotes electronic localization effects with a progressive increase of resistivity below ~25 K. Because of the larger lattice parameters the intermolecular interactions and electronic bandwidth are decreased compared to other (CNB-EDT-TTF)4X salts. The large and positive thermoelectric power S of this compound (~110 μV/K in the range 100–330 K) and its electrical conductivity σ = 20 S/cm at room temperature lead to a power factor S2σ = 24 μW/K2m, quite large among molecular conductors, placing these compounds as potential candidates for thermoelectric materials. [ABSTRACT FROM AUTHOR]

Abstract: The new compound, (bedt-ttf)[Au(cdc)2], where bedt-ttf stands for bis(3,4;3′,4′-ethylenedithio)2,2′,5,5′-tetrathiafulvalene(+) and cdc for cyanoimidodithiocarbonate(2−), was synthesised. Its structure is monoclinic, space group P21/n, with cell parameters a =6.9031(8)Å, b =21.3213(16)Å, c =7.9833(9)Å, β =91.643(6)°, V =1174.5(2)Å3 and Z =2 and consists of alternated stacking of donor and acceptor moieties along c. This compound is a semiconductor with a room temperature resistivity of 6.5×103 Ωcm and an energy gap 2Δ =0.51eV. The anisotropy and thermal dependence of the ESR signal, only due to the bedt-ttf cations, was studied in the range 4–300K. The static and EPR spin susceptibilities indicate an almost temperature independent value of 2.5×10−4 emu/mol ascribed to a three-dimensional network of antiferromagnetic interactions. [Copyright &y& Elsevier]

The charge transfer salt (DT-TTF)4[Au(pds)2]3 (DT-TTF, Δ2,2′-bithieno[3,4-d]-1,3-dithiol; pds, pyrazine-2,3-diselenate) was prepared and characterised by X-ray diffraction, electrical conductivity, thermoelectric power, magnetic susceptibility and EPR measurements. This compound crystallises in the triclinic system, space group P1¯, with the unit cell parameters a=9.712(5) A˚, b=13.620(5) A˚, c=17.169(5) A˚, α=97.254(5)°, β=106.132(5)°, γ=95.956(5)°, V=2141.10(15) A˚3, Z=1. Its crystal structure consists of a bidimensional network of DT-TTF tetramers and orthogonal anions. The electrical properties indicate it is a small gap semiconductor (2Δ=190 meV), with a room temperature conductivity of σRT=2 S cm−1. The electrical and magnetic properties reveal two types of transitions occurring upon cooling. The first, at 238 K, as a second order change to a large gap semiconducting state and, a lower transition, of first order type, with a large hysteresis between 210 and 150 K, probably associated with a larger structural change in the DT-TTF network. [Copyright &y& Elsevier]

The synthesis and characterisation of two new radical ion salts based on the donor dithiophenetetrathiafulvalene (DT-TTF) and the anion Au(cdc)2 − (cdc=cynanodithioimido carbonate) are described. These salts were characterised as the mixed valence compound (DT-TTF)2(Au(cdc)2) (1) and the completely ionic salt (DT-TTF)(Au(cdc)2) (2). The X-ray crystal structure of both compounds show that they are formed by chains of donor molecules separated by anions, but, whereas in compound 2 the donors form uniform stacks, in compound 1 they are dimerised. The electrical conductivity measured in a single crystal at room temperature is 0.2 S cm−1 for 1 and 1.7×10−2 S cm−1 for 2, both revealing semiconducting behaviour. Magnetic measurements indicate strong antiferromagnetic interactions between the donors in compound 2, and a possible spin-Peierls transition at low temperature for compound 1. [Copyright &y& Elsevier]

The conditions that allowed for the first time the growth of (Per)2[Pd(mnt)2] crystals by electrocrystallisation are described. The electrocrystallisation is limited by close proximity of the oxidation potentials of the perylene donor and [Pd(mnt)2]- anion. Depending on the experimental conditions different morphologies can be obtained. (Per)2[Pd(mnt)2] crystals were found to be mainly of the β-polymorph with properties comparable to the Cu, Ni and Pt previously described. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Electrocrystallization experiments with the chiral ethylenedithio-tetrathiafulvalene-methyl-oxazoline (EDT-TTF-OX) donors (R)-, (S)-, and (rac)-1 have provided two series of mixed-valence salts with the PF(6) (-) and [Au(CN)(2)](-) anions. Within each series the cell parameters are the same for the three R, S, and rac compounds, except for the space group, which is centrosymmetric triclinic P$\bar 1$ for the racemic forms and noncentrosymmetric P1 for the enantiopure salts. In the racemic salt [(rac)-1](2)PF(6) the two enantiomers crystallize disordered on the same crystallographic site with a site occupational factor of 0.6:0.4, whereas this type of disorder is not possible in the enantiopure salts. Both s-cis and s-trans conformations, when taking into account the mutual orientation of the TTF and oxazoline moieties, are present in this first series. In sharp contrast, in the series of salts [1](2)[Au(CN)(2)], only the s-trans conformation is observed with no structural disorder. Theoretical calculations at the DFT level of theory revealed a very small energy difference between the two stable planar s-cis and s-trans conformations, which are both energy minima in either neutral or oxidized states. Single-crystal conductivity measurements showed metallic-like behavior for all the salts down to 220-250 K with a smooth increase in resistivity at lower temperatures. The conductivity at room temperature is 5 S cm(-1) for [(rac)-1](2)PF(6), in which disorder was observed, whereas for [(R)-1](2)PF(6) and [(S)-1](2)PF(6) the average value is around 100 S cm(-1). In the second series of salts the conductivity at room temperature is 125-130 S cm(-1) for [(rac)-1](2)[Au(CN)(2)] and [(R)-1](2)[Au(CN)(2)]. Extended Hückel band structure calculations revealed identical features for the three salts of the [1](2)[Au(CN)(2)] series and are consistent with the electronic structures of quasi-one-dimensional conductors.

The gold and nickel bisdithiolene complexes based on new highly extended ligands incorporating fused tetrathiafulvalene and thiophene moieties (alpha-tdt=thiophenetetrathiafulvalenedithiolate and dtdt=dihydro- thiophenetetrathiafulvalenedithiolate), were prepared and characterised by using cyclic voltammetry, single crystal X-ray diffraction, EPR, magnetic susceptibility and electrical transport measurements. These complexes, initially obtained under anaerobic conditions as diamagnetic gold monoanic [nBu(4)N][Au(alpha-tdt)(2)] (4), [nBu(4)N][Au(dtdt)(2)] (3) and nickel dianionic species [(nBu(4)N)(2)][Ni(alpha-tdt)(2)] (8), [(nBu(4)N)(2)][Ni(dtdt)(2)] (7), can be easily oxidised to the stable neutral state just by air or iodine exposure. The monoanionic complexes crystallise in at least two polymorphs, all of which have good cation and anion segregation in alternated layers, the anion layers making a dense 2D network of short SS contacts. All of the neutral complexes, obtained as microcrystalline or quasi amorphous fine powder, present relatively large magnetic susceptibilities that correspond to effective magnetic moments in the range 1-3 mu(B) indicative of high spin states and very high electrical conductivity that in case of the Ni compound can reach sigma(RT) approximately 250 S cm(-1) with a clear metallic behaviour. These compounds are new examples of the still rare single-component molecular metals.