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New iron and cobalt bis(dithiolene) complexes [M(3cbdt)2] (3cbdt = 3-cyanobenzene-1,2-dithiolate) were prepared as tetraphenylphosphonium (Ph4P+) salts for Fe in the monoanionic state and for Co in both the dianionic and monoanionic states: (Ph4P)2[Fe(III)(3cbdt)2]2 (1); (Ph4P)2[Co(III)(3cbdt)2]2 (2); (Ph4P)2[Co(II)(3cbdt)2] (3). These compounds were characterized by single-crystal X-ray diffraction, cyclic voltammetry, EPR, and static magnetic susceptibility. Their properties are discussed in comparison with the corresponding complexes based on the isomer ligand 4-cyanobenzene-1,2-dithiolate (4cbdt) and 4,5-cyanobenzene-1,2-dithiolate (dcbdt), previously described by us. The Fe(III) and the Co(III) compounds (1 and 2) are isostructural, crystallizing in the triclinic P 1 ¯ space group, with cis [M(III)(3cbdt)2] complexes dimerized in a trans fashion, and the transition metal (M = Fe, Co) has a distorted 4+1 square pyramidal coordination geometry. The Co(II) compound (3) crystallizes in the triclinic P 1 ¯ space group, with the unit cell containing one cis and three trans inequivalent [Co(II)(3cbdt)2] complexes with the transition metal (Co) and having a square planar coordination geometry. The Fe(III) complex (1) is EPR-silent, and the static magnetic susceptibility shows a temperature dependence typical of dimers of antiferromagnetically coupled S = 3/2 spins with −J/kB = 233.6 K and g = 1.8. Static magnetic susceptibility measurements of compound (3) show that this Co(II) complex is paramagnetic, corresponding to an S = ½ state with g = 2, in agreement with EPR spectra showing in solid state a hyperfine structure typical of the I(59Co) = 7/2. Static susceptibility measurements of Co(III) complex (2) showed an increase in the paramagnetic susceptibility upon warming above 100 K, which is consistent with strong AFM coupling between dimerized S = 1 units with a constant −J/kB ~1286 K. [ABSTRACT FROM AUTHOR]

New nickel and copper bisdithiolene complexes were prepared as tetraphenylphosphonium (Ph4P+) salts, (Ph4P)n[M(3cbdt)2], [n = 1, 2; M = Ni, Cu; 3cbdt = 3-cyanobenzene-1,2-dithiolate]: (Ph4P)2[Ni(3cbdt)2] (1); Ph4P[Ni(3cbdt)2] (2); (Ph4P)2[Cu(3cbdt)2] (3); Ph4P[Cu(3cbdt)2] (4), and characterised by single crystal X-ray diffraction, cyclic voltammetry, EPR and static magnetic susceptibility for the paramagnetic species. These Cu and Ni complexes obtained as stable monoanionic and dianionic anions are the first members of this family of cyano benzene functionalized bisdithiolene transition metal complexes, opening the way to the preparation of analogous compounds with other transition metals and their future use as building blocks for the preparation of molecular materials. Their properties are discussed in comparison with the corresponding complexes based on the 4-cyanobenzene-1,2-dithiolate (4cbdt) ligand previously described by us. The salts (Ph4P)n[M(3cbdt)2], [n = 1, 2; M = Ni, Cu] present the metal complexes always in a square-planar coordination geometry with a ligand trans configuration, but revealing a rich polymorphism. The Ni and Cu compounds are isostructural and occur as two polymorphs (α, β) with the exception of the salt of the monoanionic Ni complex, that was found only as the α-polymorph. The salt of the dianionic Ni complex was found to crystallise also with one acetonitrile molecule, when recrystallised from this solvent. The salts of monoanionic [Ni(3cbdt)2] and dianionic [Cu(3cbdt)2] complexes have been characterised by EPR and static magnetic susceptibility as paramagnetic S = 1/2 species. [ABSTRACT FROM AUTHOR]

Five new salts of 5-cyanobenzene-ethylenedithio-tetrathiafulvalene (CNB-EDT-TTF), with the general formula (CNB-EDT-TTF)4A, and anions A = Ag(CN)2 (1), Ag(CN)2·H2O (2), Ag2(CN)3 (3), Ag(SCN)2 (4) and Hg2(SCN)5 (5), were prepared by electrocrystallisation and characterised by single crystal X-ray diffraction, electrical conductivity, thermoelectric power and magnetic susceptibility measurements. Their crystal structure is based on a double layer arrangement of the donors with a β′′ packing pattern identical to that previously observed in related salts with small discrete anions. The donor bilayers are separated by layers of anions which however are incoherently arranged perpendicular to the layers. The average structures obtained are compatible with anionic arrangements similar to those previously observed in single layer salts of BEDT-TTF and related donors, where, with the exception of 1, the anions are polymeric. While 2 presents electrical resistivity with a thermally activated regime, 1, 3, 4 and 5 show metallic behaviour at high temperatures, with room temperature values in the range 10–20 S cm−1 and sample dependent electronic localisation effects at lower temperatures. The thermoelectric power of these compounds is +82–90 μV K−1 at room temperature, following behavior identical to that of their analogues with small discrete anions. The paramagnetic susceptibility of 4 and 5, similar to those of their analogues with I3, PF6, AsF6 and ReO4 anions, has values of ≈1.0 × 10−3 emu mol−1 at room temperature, being significantly enhanced compared with the Pauli-type contribution predicted from electron band calculations. [ABSTRACT FROM AUTHOR]

Four salts of the dissymmetric TTF-derivative 4-cyanobenzene-ethylenedithio-tetrathiafulvalene (4-CNB-EDT-TTF) with different anions, namely (4-CNB-EDT-TTF)A with A = ClO4 (1), BF4 (2) and (4-CNB-EDT-TTF)2[M(mnt)2] with M = Ni (3) and Au (4), were obtained by electrocrystallization and characterized by single-crystal X-ray diffraction, magnetic susceptibility and electrical conductivity measurements in comparison with the analogues based on the donor 5-CNB-EDT-TTF. All the compounds present dimerization of the donor units. Compounds 1 and 2 are isomorphous with a crystal structure characterized by slipped head to tail donor dimer stacks segregated from anion columns. Compounds 3 and 4 are isostructural with a crystal structure characterized by alternated stacks of head to tail donor dimers and acceptors. In spite of the different structural types and stoichiometries, all of these compounds have C≡N⋯H pairing interactions associated with R 22 (8), R 24 (8), R 22 (10), and R 24 (10) synthons between donors in nearby dimers. 3 and 4 are semiconductors, and their magnetic susceptibility exhibits a behaviour typical of antiferromagnetically coupled spin chains with magnetic exchange values J/k = −149.9 and −60.1 K, respectively, and in the case of 3, a Curie–Weiss contribution from the paramagnetic anions [Ni(mnt)2]−. [ABSTRACT FROM AUTHOR]

Gold and nickel bisdithiolene complexes with methyl and tert-butyl substituted thiophenetetrathiafulavalenedithiolate ligands (α-mtdt and α-tbtdt) were prepared and characterized. These complexes were obtained, under anaerobic conditions, as tetrabutylammonium salts. The diamagnetic gold monoanion (n-Bu4N)[Au(α-mtdt)2] (3) and nickel dianionic species (n-Bu4N)x[Ni(α-mtdt)2] (x = 1,2) (4) were similar to the related non-substituted extended thiophenic-TTF (TTF = tetrathiafulvalene) bisdithiolenes. However the introduction of the large, bulky substituent tert-butyl, led to the formation of a Au (I) dinuclear complex, (n-Bu4N)2[Au2(α-tbtdt)2] (5). The neutral methyl substituted gold and nickel complexes were easily obtained through air or iodine exposure as polycrystalline or amorphous fine powder. [Au(α-mtdt)2] (6) and [Ni(α-mtdt)2] (7) polycrystalline samples display properties of a metallic system with a room temperature electrical conductivity of 0.32 S/cm and ≈4 S/cm and a thermoelectric power of ≈5 µV/K and ≈32 µV/K, respectively. While [Au(α-mtdt)2] (6) presented a Pauli-like magnetic susceptibility typical of conducting systems, in [Ni(α-mtdt)2] (7) large magnetic susceptibilities indicative of high spin states were observed. Both electric transport properties and magnetic properties for gold and nickel [M(α-mtdt)2] are indicative that these compounds are single component molecular conductors. [ABSTRACT FROM AUTHOR]

Three salts of the dissymmetrical TTF derivative cyanobenzene-ethylenedithio-tetrathiafulvalene (CNB-EDT-TTF) with different anions, namely, (CNB-EDT-TTF)2[M(mnt)2] [M = Ni ( 1), Au ( 2); mnt = maleonitriledithiolate] and (CNB-EDT-TTF)FeBr4 ( 3) were prepared and characterized by single-crystal X-ray diffraction, magnetic susceptibility, and electrical conductivity measurements. Compounds 1 and 2 are isostructural with a crystal structure characterized by segregated chains of side-by-side donor dimers and acceptors, and compound 3 presents donors in dimerized stacks. In spite of the different structural types and stoichiometries, all of these compounds have C-N ···H pairing interactions associated with R22(10) synthons between donors in nearby chains. All compounds are poor semiconductors, and the magnetic susceptibility of 1 is dominated by the contribution of the paramagnetic [Ni(mnt)2] anions with small antiferromagnetic interactions. The magnetic susceptibility of 3 is dominated by the paramagnetic FeBr4 anions and follows a Curie-Weiss law with a Weiss temperature θ = -19 K, which denotes significant antiferromagnetic interactions that are most likely mediated by the donors. [ABSTRACT FROM AUTHOR]

Abstract: A series of new [M(cbdt)2] z − complexes of the 4-cyanobenzene-1,2-dithiolate (cbdt) ligand with a range of transition metals M (M=Zn, Co, Cu, Au, Ni, Pd) were prepared in different oxidation states (z =0, 1, 2) as salts with several cations and characterised by X-ray diffraction, cyclic voltammetry, EPR and static magnetic susceptibility. Their properties are discussed in comparison either with the Fe analogue or corresponding complexes based on the dicyano substituted ligand (dcbdt) previously described by us. These complexes can be prepared either from the ligand dithiol as previously described for the Fe analogue, or in a more convenient way to obtain the more reduced forms, from the 4-cyanobenzene-1,3-dithiole-2-thione (1) which is described here for the first time. The structure of these complexes presents square planar coordination geometry, and belong to four distinct groups: (i) the Au monoanionic compound 4a is monoclinic, C 2/c, where the complex presents a cis–trans disorder; (ii) the compounds 10b, 7b of the dianionic Pd and Ni complexes, are isostructural, monoclinic, P21/c, with the metal in an inversion centre, a perfect square-planar coordination geometry and a ligand trans configuration; (iii) the compounds (8a and 9a) of the Co and Cu dianionic complexes, which are monoclinic P21, with the metal located in a general position with square planar coordination and ligand trans configuration; and (iv) the monoanionic Cu compound 12 is triclinic, , with the metal in a general position with almost ideal square-planar coordination and ligand trans configuration. These complexes present redox properties intermediate between those based on dcdbt and unsubstituted benzenedithiolate ligand (bdt), and the gold complex can be obtained in the neutral state. The EPR and static magnetic susceptibility measurements show that the dianionic cobalt and copper complexes (8a and 9a) the monoanionic nickel (3), and the neutral gold (11) complexes are paramagnetic corresponding to an S =½ state. The powder EPR spectrum of the dianionic Co complex 8a presents a hyperfine structure typical of I =7/2 59Co with a component a 0 x =8.6mT. [Copyright &y& Elsevier]

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]

Abstract: The Ni and Au bis(dithiolene) complexes based on the 1-(pyridine-4-yl)-ethylene-1,2-dithiolate ligand were prepared in their neutral state and characterized namely by single-crystal X-ray diffraction, electronic UV–Vis–NIR spectroscopy, EPR and magnetic susceptibility measurements. The crystal structure of the neutral complex [Ni(4-pedt)2]0 lacks a regular and multidimensional extended network of short contacts and as a consequence electrical conductivity measurements in single crystals show a semiconducting behavior with room temperature values of the order of 10−6 S/cm, while the magnetic measurements of the gold compounds indicate a reduced effective magnetic moment due to strong antiferromagnetic interactions between radical neutral complex units. The nitrogen coordination ability of theses complexes was demonstrated by the coordination of pyridine to a sodium ion observed in the [Au(4-pedt)2]2NaPF6 complex which was also characterized by single-crystal X-ray diffraction and magnetization. In this compound the Na ions in half occupied positions are coordinated by anion fluorine atoms and nitrogen and carbon atoms from the neutral [Au(4-pedt)2] complexes. [Copyright &y& Elsevier]