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 P1¯ 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 P1¯ 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.

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 (& alpha;, & beta;) with the exception of the salt of the monoanionic Ni complex, that was found only as the & alpha;-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. New nickel and copper cyanobenzene-functionalised bisdithiolene transition metal complexes reveal a rich polymorphism and pave the way for analogous compounds with other transition metals as building blocks for molecular materials.

Two salts of the dissymmetric TTF-derivative 4-cyanobenzene-ethylenedithio-tetrathiafulvalene (4-CNB-EDT-TTF) with bromide and tribromide anions and with different stoichiometries, namely, (1:1) (4-CNB-EDT-TTF)Br-3 (1) and (4:1) (4-CNB-EDT-TTF)(4)Br (2), were obtained by electrocrystallization and diffusion methods, respectively. The crystal structures of these compounds, as determined by single-crystal X-ray diffraction, are based on head-to-tail donor dimers with ring over ring overlap and donor stack arrangement, interleaved by anions depending on the (1:1) or (4:1) salt, respectively. The 4:1 salt behaves as a Mott insulator. In both salts, the donors are connected to adjacent donors through C-N center dot center dot center dot H-C interactions, which can be described as an modified R-4(2) (10)* synthon for 1 and a combination of R-2(2) (10) and R-4(2)(10) synthons for 2.

A new isomer of the dissymmetric TTF derivative, 4-cyanobenzene-ethylenedithio-tetrathiafulvalene (4-CNB-EDT-TTF) (1), was prepared and compared with the previously reported 5-CNB-EDT-TTF.

Radical cation salts of 4-CNB-EDT-TTF presenting CN⋯H pairing interactions, semiconducting properties and chains of antiferromagnetically coupled donor dimers.

Three salts of the two isomers of the dissymmetric TTF‐derivative cyanobenzene‐ethylenedithio‐tetrathiafulvalene (CNB‐EDT‐TTF) with binuclear polyhalide complex dianions, namely [4‐CNB‐EDT‐TTF]2 [Cu2Cl6] (1); [5‐CNB‐EDT‐TTF]2 [Cu2Cl6] 2CH2Cl2 (2) and [5‐CNB‐EDT‐TTF]2 [Hg2Br6] (3) were prepared and characterized by single‐crystal X‐ray diffraction and magnetic susceptibility measurements. In spite of the different structural types of these compounds, the three compounds present donors in dimerized stacks. The crystal structures of 1 and 3 consist of segregated head‐to‐tail donor dimer stacks and dianion columns. The structural motif of 2 is mixed columns of alternating head‐to‐tail donor dimers and dianions. The three salts present C–N···H–C interactions, which in 2 and 3 can be described as a R22(10) synthon. The magnetic susceptibility of the salts with the paramagnetic (Cu2Cl6)2– dianion (1 and 2) show that they behave as paramagnets where the Cu2+ atoms of the dianion are antiferromagnetically coupled with magnetic exchange values J/kB of –58.8 and –155.6 K, respectively. The different J values are associated with differences in dianion geometry.