Tellurium-Halogen Compounds

Tellurium-Halogen Compounds.—Enthalpies and entropies of evaporation of TeCU and of sublimation of TeBr4 have been measured. Using the above data, the equilibrium constant of the reaction  

Bachmann, and V. Matschoss, J. Inorg. Nuclear Chem., 1975, 37, 1577. 

Agranat, M. Rabinovitz, and H. Sclig, Inorg. Nuclear Chem. Letters, 1975,11, 185. 

The heats of formation of potassium, rubidium, and caesium hexachlorotellu-rates(iv) have been found from their heats of solution, and those of crystalline TeCU and the metal chlorides determined from isothermal calorimetry. Thermal and elastic properties of the alkali-metal hexachlorotellurates have also been investigated. Spectroscopic studies on a series of dialkyltellurium tetraiodides have been carried out.  

The solvated entities Te , Teo, and Tel have been identified in reaction mixtures of dilute solutions of TeCU and elemental tellurium in the low-melting NaCl-AlCl3(37 63 mol%) solvent at 250 The enthalpy of formation of the complex ion TeCl has been determined as AHf=-1020.4 kJmorS and the affinity of gaseous TeCU for chloride ion to be -304.1 kJ mor  

and Raman spectra of TeClFs have been recorded, and assignments made on the basis of C4 symmetry. A normal-co-ordinate analysis was carried out on SCIF5, SeClFs, TeClFj, SFg, SeF, and TeFg, and the derived force constants were compared. 

The sublimation and the decomposition of Tel4 have been investigated. For the sublimation and the decomposition reactions (39) and (40), the values of enthalpy 

The conproportionation of diaryl ditellurides and aryltellurium trihalides, resulting in the formation of aryltellurenyl halides, has been investigated. The aryltellurenyl halides are, in general, unstable, and they disproportionate to diaryltellurium dihalides and elemental tellurium.  

In agreement with earlier work, tellurium tetrafluoride oxide dimer has been found to be strongly oxygen-bridged, in sharp contrast to tungsten tetrafluoride oxide, which is weakly fluorine-bridged in the solid state but which readily dissociates to a square-pyramidal monomer. Despite variable-temperature i.r. and Raman studies, no trace of reversible equilibria involving a terminal Te—O bond was detected 

Crystallographic data for the subhalides of telluriiun are given in Table 2. 

An investigation of the electron-acceptor properties of TeCl4 with some donor molecules (sulphides, ethers, ketones, and sulphoxides) has been carried out. Enthalpies of formation and dipole moments of the complexes were measured and the heats of the reaction  

The crystal structure of the 1 1 adduct TeCl4,PCl5 has been determined. The compound crystallizes in the orthorhombic space group /ma2, with 

When a solution of equimolar amounts of tellurium(iv) chloride and triphenylmethyl chloride in benzene is warmed gently, a dark brown solution 

Rb2TeBre. The reaction of H2TeBrj with several amines in acetic acid has been shown to give compounds of the type LgHgTeBr and L4H2TeBrj. The chemical composition and solubility of the products were studied in different solvents. 

The hydrolysis of TeF6 has been shown357 to produce the fluoro-ortho-telluric acids TeF (OH)6- , where n = l—4, which undergo complete hydrolysis to ortho telluric acid only over a long period of time. The presence of the fluoro-orthotelluric acids, together with the fully hydrolysed ortho-telluric acid, was observable even after ten days. This work therefore conflicts with the older and much quoted observation (E. B. R. Prideaux, J. Chem. Soc., 1906, 316) that TeF6 is completely hydrolysed in 24 hours to Te03 and HF. 

Both compounds showed unexpectedly high thermal stability since rapid decomposition does not occur below 150 °C. The conclusion was drawn that H2NTeF5 is a weaker base than its sulphur analogue and that the lower basicity of the nitrogen in H2NTeF5 compared to H2NSF5 may be a further reason for the greater stability of the tellurium compound. 

Inorganic Chemistry of the Main-group Elements are weakly linked through water molecules interacting with the Te and O (or OH) groups to form an infinite chain structure. 

The phase systems CoCl2-NaCl-TeCl4,37° TeBr4-MBr (M = Cu, Ag, or Tl),371 and TeI4-MI (M = Li, Cu, Ag, or Tl)372 have been studied. 

The determination of the structures of the known subhalides of tellurium has now been completed by the determination373 of the crystal structures of a- and 3-TeI. The macromolecular structural unit of 3-TeI consists of a zigzag chain of tellurium atoms running parallel to the crystallographic b- axis, the atoms having alternate square-planar and trigonal-pyramidal co-ordination (66). Correspondingly, there are two independent iodine 

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Tellurium-Halogen Compounds.—The first investigation of the structures of the recently prepared tellurium subhalides Te X (X = Cl, Br, or I, y > 1) has been reported. The building unit of TesClg is shown in Figure 8 an infinite tellurium screw, such as is present with a simpler conformation and higher symmetry in elemental tellurium, is observed. Each third Te atom... 

Synthesis, reactivity, and applications of sulphur- selenium-, and tellurium-halogen compounds electronic structure and bonding of hypervalent compounds of the heavy main group elements... 

A novel class of chalcogen(II) halogen compounds was established recently by the preparation of the first simple binary mononuclear and oligomeric haloanions of divalent selenium and tellurium. The chemistry of these compounds is especially variable for selenium, and a number of highly interesting mono-, di-, tri, tetra- and pentanuclear anionic species with composition X Ym have been synthesized and characterized by structure analyses and spectroscopic studies up... 

Compound classes, not previously described (eg. 5- and 6-membered heteroarenes) Compound classes, for which, in the meantime, significant improvements and progresses have been made, for example carbonic acid derivatives, carboxylic acids and carboxylic acid derivatives, aldehydes, carbonyl derivatives, halogen compounds, peroxides, sulfur, selenium, tellurium, nitrogen and phosphorus compounds. 

Molecular structure and thermochemistry are interrelated here for species chosen from contributions to the earlier Volume 3 of this book series. Discussion includes halogenated species gaseous nonmetal dioxides X-Y bond-containing species (X,Y = C, N, O) small carbon molecules arenols and substituted arenes steroids aromatic carbocycles difluoramines and nitro compounds selenium- and tellurium-nitrogen compounds. 

Sihcon and boron bum ia fluorine forming siUcon tetrafluoride [7783-61-17, SiF, and boron trifluoride [7637-07-2] respectively. Selenium and tellurium form hexafluorides, whereas phosphoms forms tri- or pentafluorides. Fluorine reacts with the other halogens to form eight interhalogen compounds (see Fluorine compounds, inorganic-halogens). 

Nitrogen and sodium do not react at any temperature under ordinary circumstances, but are reported to form the nitride or azide under the influence of an electric discharge (14,35). Sodium siHcide, NaSi, has been synthesized from the elements (36,37). When heated together, sodium and phosphoms form sodium phosphide, but in the presence of air with ignition sodium phosphate is formed. Sulfur, selenium, and tellurium form the sulfide, selenide, and teUuride, respectively. In vapor phase, sodium forms haHdes with all halogens (14). At room temperature, chlorine and bromine react rapidly with thin films of sodium (38), whereas fluorine and sodium ignite. Molten sodium ignites in chlorine and bums to sodium chloride (see Sodium COMPOUNDS, SODIUM HALIDES). 

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