Introducing Selenium in Single-Component Molecular Conductors Based on Nickel Bis(dithiolene) Complexes
Résumé
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 (σ(RT) = 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.
Domaines
Chimie de coordination
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Hachem_et al_2021_Introducing selenium in single component_accepted.pdf (1.31 Mo)
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Hachem_et al_2021_Introducing selenium in single component_suppl data.pdf (1.25 Mo)
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