The first examples of chiral single component conductors are reported. Both (S,S) and (R,R) enantiomers of 5,6-dimethyl-5,6-dihydro-1,4-dithiin-2,3-dithiolate (dm-dddt) ligand have been used to prepare anionic metal bis(dithiolene) complexes formulated as ([(n-Bu)4N][M(dm-dddt)2] (M = Au, Ni), which are isostructural according to single crystal X-ray analysis. Single crystal transport measurements indicate semiconducting behavior for the anionic radical Ni complexes, with low room temperature conductivity values and high activation energies. Electrocrystallization experiments provided neutral [M(dm-dddt)2] (M = Au, Ni) complexes. The neutral radical gold compounds show intermolecular S···S interactions in the solid state giving rise to layers interconnected through weak C-H···S hydrogen bonds. The most peculiar structural feature concerns a dissymmetry between the two dithiolene moieties, while the nickel counterpart is symmetric. Single crystal resistivity measurements show thermally activated behavior for the open-shell gold complexes, with room temperature conductivity values of 0.02-0.04 S·cm(-1) and activation energies strongly influenced by hydrostatic pressure. A thorough theoretical study on nickel anion radical and gold neutral radical bis(dithiolene) complexes applied to the chiral complexes [M(dm-dddt)2] (M = Au, Ni(-)) and to a series of previously reported compounds addressed the issue of symmetry versus asymmetry from an electronic coupling perspective between the two dithiolene ligands. It results that neutral gold complexes with dithiolene ligands without extended delocalization are Class II mixed-valent compounds in the Robin and Day classification, presenting an inherent tendency toward asymmetric structures, which can be however modulated by the intermolecular organization in the solid state.

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An azobenzene based iminopyridine ligand 1 has been synthesized by a condensation reaction between N,N-dimethyl-4,4′-azodianiline and 2-formylpyridine. The complexation of the ligand with ZnCl2 afforded a tetrahedral neutral zinc metal complex (2) formulated as [(Azo-Imino-Py)ZnCl2]. The crystal structure analysis of the complex indicates the formation of a tetracoordinated zinc(II) ion with the expected tetrahedral geometry. In solid state, a 2D supramolecular architecture reinforced by π–π stacking and hydrogen bonding is observed. The UV–visible spectrophotometric titration studies of the ligand, by increasing amount of ZnCl2, confirm the existence of single complex species in solution. The nonlinear optical (NLO) investigations by Z-scan technique of both ligand 1 and complex 2 indicate a dramatic enhancement of the NLO absorption of the ligand upon complexation with ZnCl2. This enhancement is likely to be due to a large dipole moment found for the complex 2 as calculated by DFT/B3LYP methodology.