Issue 9, 2001
From the journal:

Journal of Materials Chemistry

C. Faulmann,*a   M.-L. Doublet,*b   F. Granier,b   B. Garreau de Bonneval,a   I. Malfant,a   J.-P. Legros,a   T. Togonidzec  and  P. Cassouxa  

* Corresponding authors

a Laboratoire de Chimie de Coordination, CNRS, 205 route de Narbonne, Toulouse Cedex, France
E-mail: faulmann@lcc-toulouse.fr

b Laboratoire de Structure et Dynamique des Systèmes Moléculaires et Solides USTL II, Place Eugène Bataillon, Montpellier Cedex 5, France
E-mail: doublet@lsd.univ-montp2.fr

c Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow Distr., Russia

Abstract

The previously mentioned (SMeEt2)[Pd(dmit)2]2 (1) and the new (SMeEt2)0.5[Pd(dmit)2] (2) phases are obtained by electrocrystallisation of (SMeEt2)2[Pd(dmit)2] in acetonitrile. The crystal structures of 1 and 2 are determined by X-ray diffraction methods, both at room and low temperatures. Though not previously detected, a cation disorder is evidenced in both phases at room temperature which is removed in 1 at low temperatures. Conductivity measurements show a rather smooth metal to insulator transition in the 150–200 K range for 1 whereas 2 behaves as a semiconductor in the whole range of temperature. Under pressure, the transition of 1 is shifted down to lower temperatures and becomes more abrupt. Electronic band structure calculations (by means of the extended Hückel tight-binding model) show that the cation disorder evidenced in 1 is responsible for two different electron transfers occurring from the (SMeEt2)+ cation layers to the two crystallographically independent anion layers, resulting thus in the observed room temperature metal-like behaviour of 1. The ambient pressure phase transition of 1 is shown to be the consequence of a more homogeneous electron transfer, possibly leading to a Mott–Hubbard localised state at low temperatures, as is also the case for 2. Under pressure, the more abrupt phase transition observed in 1 is believed to originate from a different metallic regime.

Graphical abstract: Synthesis, electrical behaviour, and crystal and electronic band structures of two different phases of the (SMeEt2)[Pd(dmit)2]2 salt. Consequences of cationic disorder on the electrical properties

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Article information

DOI
https://doi.org/10.1039/B102133H
Article type
Paper
Submitted
07 Mar 2001
Accepted
27 Apr 2001
First published
07 Jun 2001

J. Mater. Chem., 2001,11, 2205-2210

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Synthesis, electrical behaviour, and crystal and electronic band structures of two different phases of the (SMeEt2)[Pd(dmit)2]2 salt. Consequences of cationic disorder on the electrical properties

C. Faulmann, M.-L. Doublet, F. Granier, B. Garreau de Bonneval, I. Malfant, J.-P. Legros, T. Togonidze and P. Cassoux, J. Mater. Chem., 2001, 11, 2205 DOI: 10.1039/B102133H

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