Short and directional I⋯S halogen bonding interactions in iodinated bis(dithiolene) complexes lead to the crystallization of 2D or 3D anionic frameworks.

Neutral, closed-shell nickel and platinum bis(dithiolene) complexes are explored as single-component conductors. Four complexes formulated as [Ni(R-thiazdt)2]0 and [Pt(R-thiazdt)2]0 (R-thiazdt: 2-alkyl-1,3-thiazoline-2-thione-4,5-dithiolate; R = Me, Et) were obtained by electrocrystallization from...

Nickel (closed-shell) or gold (radical) bis(dithiolene) neutral complexes, functionalized with hydroxyethyl and thiazole moieties, afford hydrogen-bonded single component conductors.

Two selenated analogues of the all-sulfur single-component molecular conductor [Ni­(Et-thiazdt)2] (Et-thiazdt = N-ethylthiazoline-2-thione-4,5-dithiolate) have been prepared from their precursor radical-anion complexes. Replacement of the thione by a selenone moiety gives the neutral [Ni­(Et-thiazSedt)2] complex. It adopts an unprecedented solid-state organization (for neutral nickel complexes), with the formation of perfectly eclipsed dimers and very short intermolecular Se···Se contacts (81% of the van der Waals contact distance). Limited interactions between dimers leads to a large semiconducting gap and low conductivity (σRT = 1.7 × 10–5 S cm–1). On the other hand, going from the neutral [Ni­(Et-thiazdt)2] dithiolene complex to the corresponding [Ni­(Et-thiazds)2] diselenolene complex gives rise to a more conventional layered structure built out of uniform stacks of the diselenolene complexes, different, however, from the all-sulfur analogue [Ni­(Et-thiazdt)2]. Band structure calculations show an essentially 1D electronic structure with large band dispersion and a small HOMO–LUMO gap. Under high pressures (up to 19 GPa), the conductivity increases by 4 orders of magnitude and the activation energy is decreased from 120 meV to only 13 meV, with an abrupt change observed around 10 GPa, suggesting a structural phase transition under pressure.

Abstract:The interplay between two extended tetrathiafulvalenes connected, either from the dithiole rings or the

Highly conducting, mixed-valence, multi-component nickel bis(diselenolene) salts were obtained by electrocrystallization of the monoanionic species [Ni(Me-thiazds)2]−1 (Me-thiazds: N-methyl-1,3-thiazoline-2-thione-4,5-diselenolate), with 1:2 and 1:3 stoichiometries depending of the counter ion used (Et4N+ and nBu4N+ vs Ph4P+, respectively). This behavior strongly differs from that of the corresponding monoanionic dithiolene complexes whose oxidation afforded the single component neutral species. This provides additional rare examples of mixed-valence conducting salts of nickel diselenolene complexes, only known in two examples with the dsit (1,3-dithiole-2-thione-4,5-diselenolate) and dsise (1,3-dithiole-2-selone-4,5-diselenolate) ligands. The mixed-valence salts form highly dimerized or trimerized bi- and trimetallic units, rarely seen with such nickel complexes. Transport measurements under a high pressure (up to 10 GPa) and band structure calculations confirm the semiconducting character of [Ph4P][Ni(Me-thiazds)2]3 and the quasi metallic character of [Et4N][Ni(Me-thiazds)2]2 and [NBu4] x [Ni(Me-thiazds)2]2 salts (0 < x < 1).

Neutral nickel bis(dithiolene) complexes, because of their closed-shell character, are usually considered as insulating materials, unless they are formed out of highly delocalized tetrathiafulvalenedithiolate ligands. We describe here an original series of S-alkyl substituted neutral bis(thiazole-4,5-dithiolate) nickel complexes formulated as [Ni(RS-tzdt)2] (R = Me, Et), which organize in the solid state into uniform stacks and exhibit semiconducting behavior, with room temperature conductivities comparable to those reported in the prototypical [Ni(dmit)2] and [Ni(Et-thiazdt)2] neutral complexes. These findings provide new perspectives in the current search for single component molecular conductors.

The prototypical [Ni(dmit)2] complex (dmit: 1,3-dithiole-2-thione-4,5-dithiolate) is modified here by combining the N−R substitution found in [Ni(R-thiazdt)2] complexes (R-thiazdt: N-alkyl-thiazoline-2-thione-4,5-dithiolate) and the selone substitution found in [Ni(dmiSe)2] complex (dmiSe: 1,3-dithiole-2-selone-4,5-dithiolate)...