Heat indium compounds

The sulphides M2S3 are all made by direct combination of the elements. But GaS is also known and has an unusual layer lattice containing Ga2 ions (Hahn and Frank, 1955). The nitride GaN,unreactive to water and acids, is made by heating gallium in ammonia at 1000° the corresponding indium compound is best made by heating (NH4)3lnFg. Both have the wurtzite lattice. 

Table 4.1-79 Heat capacity Cp and Debye temperature 6>d of indium compounds...

The high degree of reactivity can be seen by comparing the literature preparation of these indium compounds. For example, Dennis prepared (CH3)3ln from indium metal and (CH3)2Hg by heating at 100°C for 8 days, and no yield was reported. However, when (CH3)2Hg was allowed to react with the activated indium metal, the reaction reached 100% yields after only 3 h at 100°C. Similarly, the preparation of the triaryl indium compounds is greatly facilitated by using the activated indium metal, and the yields are essentially quantitative. 

Thallium phthalocyanine (PcT12) can be obtained by heating phthalonitrile with an inter-metallic alloy of indium and thallium in an evacuated glass ampule.145 The structure of this compound is unique among metal phthalocyanines as the two thallium cations occupy two opposite corners of an octahedron, which is formed by the thallium cations and the four iso-indolinc nitrogen atoms facing the center of the macrocycle.147 Another unusual type of phthalocyanine can be prepared by heating phthalonitrile with thallium metal.148 It was identified as a bicyclic thallium(III) phthalocyanine (Pc3/2T1).14S... 

In 1991, Li and Chan reported the use of indium to mediate Barbier-Grignard-type reactions in water (Eq. 8.49).108 When the allylation was mediated by indium in water, the reaction went smoothly at room temperature without any promoter, whereas the use of zinc and tin usually requires acid catalysis, heat, or sonication. The mildness of the reaction conditions makes it possible to use the indium method to allylate a methyl ketone in the presence of an acid-sensitive acetal functional group (Eq. 8.50). Furthermore, the coupling of ethyl 2-(bromomethyl)acrylate with carbonyl compounds proceeds equally well under the same reaction conditions, giving ready access to various hydroxyl acids including, for example, sialic acids. 

Tris(0-ethyl dithiocarbonato)chromium(III) is obtained as a dark blue crystalline powder which decomposes at 100 to 140°. The indium(III) ethylxanthate complex forms small colorless crystals which decompose at 130 to 150°.16,17 The cobalt (III) ethylxanthate complex is isolated as a dark green crystalline powder whose decomposition temperature determined by use of a thermal balance is 135 to 137° (lit. value, 117° 2 118 to 119°8). These compounds decompose slowly in air and more rapidly when heated in solution. The tripositive chromium, indium, and cobalt complexes are insoluble in water but are soluble in many organic solvents (Table T). 

Indium also has many of the characteristics that make Al and Ga very useful for such applications. Particularly important is its capacity to dissolve Si, Ge and several lanthanide and transition metals, producing highly reactive forms of the elements. Moreover In does not form binaries with Si and Ge and has a low-melting point. RNiGe2 compounds, for instance, were prepared from stoichiometric quantities of the components in fine powder mixed with a 10 fold quantity of In in alumina tubes. These, flame sealed in fused silica tubes, were slowly heated to 1000°C, held at this temperature for a few hours, ramped down to 850°C, held for an additional 4 days and finally cooled down to room temperature over the course of another 4 days. Compound isolation from the In excess was performed by centrifugation at 300°C through a coarse frit. Further purification was carried out by a 15-minute submersion and sonication in 6 M aqueous HC1 (Salvador et al. 2004). 

SAFETY PROFILE A poison by ingestion, skin contact, and intraperitoneal routes. Vigorous reaction with indium at 350°C. Incompatible with sodium and potassium. When heated to decomposition it emits v rj toxic fumes of Br and Hg. See also MERCURY COMPOUNDS and BROMIDES. 

The metal indium has so far only yielded one derivative, indium diphenyl chloride. This was isolated by the interaction of mercury diphenyl and metallic indium in boiling xylene. It is an insoluble compound, not melting at 350 C. When metallic indium and mercury diphenyl are heated at 270 C. in a nitrogen atmosphere under reduced... 

Thallium (10 % of earth s crust) is recovered principally from the flue dust of pyrites burners. The soft, grey metal, which has a hexagonal close-packed structure, is rather more reactive than gallium and indium because of the ease with which it forms a unipositive ion. It oxidises in moist air, decomposes steam at red heat and dissolves readily to form thallium(I) compounds in dilute mineral acids other than HCl, because of the insolubility of TlCl. 

Only boron, the first element in Group 13, is a metalloid. The other Group 13 elements—almninum (Al), gaUimn (Ga), indium (In), and thal-limn (Tl)—are metals. None of the metals are as active as the metals in Groups 1 and 2, but they re good conductors of heat and electricity. They are silvery in appearance and fairly soft. Group 13 metals tend to share electrons rather than form ionic compoimds in this respect, they resemble boron. Their valence configuration is and they exhibit the 3+ oxidation number in most of their compounds. 

Sulfur forms three binary compounds with indium, In2S, InS, and In2S3. The latter is prepared by direct union of the elements, by heating ln208 with sulfur or H2S or by passing H2S into the weakly acid solution of an indium salt. The precipitated form is yellow, and the salt formed by dry methods varies from yellow to brown. It is soluble in mineral acids, readily forms colloidal solutions, and gives complex salts with the alkali sulfides, such as K2In2S . 

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