Synthesis and structural characterization of transition metal dithiolene derivatives containing divalent metals as counter-cations

Complexes containing [Fe₂(SC₆H₂Cl₂S)₄]²⁻ or [Ni(SC₆H₂Cl₂S)₂]⁻ entities and divalent metal cations as well as an 1D-coordination polymer K/Zn have been obtained and their magnetic behaviour studied.

Coordination polymers based on diiron tetrakis(dithiolato) bridged by alkali metals, electrical bistability around room temperature, and strong antiferromagnetic coupling

Coordination polymer chains have been formed by the direct reaction between HSC6H2Cl2SH and FeCl3·6H2O in the presence of an aqueous solution of the corresponding alkali-metal hydroxide (M = Li, Na, and K) or carbonate (M = Rb and Cs). The structures consist of dimeric [Fe2(SC6H2Cl2S)4](2-) entities bridged by [M2(THF)4] [M = K (1), Rb (2), and Cs (3); THF = tetrahydrofuran] or {[Na2(μ-H2O)2(THF)2] (5 and 5') units. The smaller size of the lithium atom yields an anion/cation ion-pair molecule, [Li(THF)4]2[Fe2(SC6H2Cl2S)4] (4), in which the dianionic moieties are held together by Cl···Cl interactions. Electrical characterization of these compounds shows a general semiconductor behavior in which the conductivity and activation energies are mainly determined by the M-Cl and M-S bond distances. Compounds 1 and 5' are interesting examples of bistability showing reversible transitions centered at ca. 350 and 290 K with very large hysteresis of ca. 60 and 35 K, respectively. All of these compounds exhibit intradimer strong antiferromagnetic Fe···Fe interactions.

Bis(triethyl-ammonium) bis-(μ-pyrazine-2,3-dithiol-ato)bis-(pyrazine-2,3-dithio-lato)diferrate(III) methanol disolvate

In the title compound, (C₆H₁₆N)₂[Fe₂(C₄H₂N₂S₂)₄]·2CH₄O, the [Fe^III(pdt)₂]⁻ anion (pdt is pyrazine-2,3-dithiol­ate) forms a centrosymmetric dimer supported by two Fe^III—S bonds [Fe—S = 2.4787 (4) Å]. In the crystal structure, dimers form a one-dimensional stack along the b axis via π–π stacking inter­actions, the inter­planar separation between adjacent dimers being 3.51 (2) Å. The methanol solvent mol­ecule is involved in two hydrogen bonds in which the hydroxyl group acts as a hydrogen-bond donor to the N atom of a pdt ligand and the O atom acts as an acceptor for the NH group of the triethyl­ammonium cation.