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Graphit einlagerungsverbindungen mit thallium(III) chlorid

1978; Elsevier BV; Volume: 16; Issue: 4 Linguagem: Inglês

10.1016/0008-6223(78)90038-6

1873-3891

E. Stumpp, Roland Niess,

Inorganic Chemistry and Materials

Whilst graphite lamellar compounds with AlCl3, GaCl3 and InCl3[1,2] have been extensively studied, the analogous compounds with TlCl3 have received scant attention although it has been known for many years that TlCl3 forms intercalation compounds [4,5]. As a part of a systematic investigation of metal halide graphite compounds [8] we studied the system TlCl3/graphite in detail. TlCl3-graphite compounds were prepared by heating mixtures of anhydrous TlCl3 and graphite in sealed tubes. The reaction conditions are summarized in Table 1. In method (I) the tubes had been evacuated, in (II) filled with nitrogen, and in (III) filled with chlorine. In (IV) the tubes contained 2 ml liquid chlorine before sealing. In (V) TlCl instead of TlCl3 was heated with graphite in chlorine vapor. The samples were washed with methanol saturated with chlorine. Table 1 shows that the preparation of TlCl3-graphite is best affected by heating up to 150°C in the presence of chlorine. Samples 10 and 11, obtained in inert atmosphere, were only of the 2nd stage type. They were contaminated with TlCl and mixed Tl(I)-Tl(III) chlorides. In this case the chlorine, the presence of which is a basic requirement for intercalation, had been generated by dissociation of TlCl3. The metal: chlorine ratios in samples having been prepared in chlorine vapor resemble those in AlCl3-graphite[2]. Accordingly the TlCl3-graphite can be formulated as Cn+[TlCl4−]·XTlCl3 (X = 2.5–3). Preparation of TICl3-graphite (1st stage) was also accomplished by refluxing a solution of TlCl3 in SOCl2 or in SO2Cl2 with graphite with or without bubbling chlorine through the solution. The results are listed in Table 2. Reaction of graphite with TlCl3 in nitromethane gave only a 2nd stage compound. The ease of intercalation of TlCl3 in the three solvents follows the order: SO2Cl2 > SOCl2 > NM. This is explained with the different Gutmann donor numbers [11] of the solvents. Compound formation was verified by means of X-ray diffraction. The reflexes of a 1st stage compound are listed in Table 5. The identity period along the c-axes is Ic = 977 ± 5 pm for the 1st stage, 1312 pm for the 2nd stage, and 1645 pm for the 3rd stage. The intercalated TlCl3 is considerably more stable than the free TlCl3 which decomposes above 100°C. No explanation can be given why AlCl3, GaCl3, and TlCl3 form the 1st stage compound whereas with InCl3 only the 2nd stage could be obtained.