Tellurium molecular structures

Structural steels, tellurium in, 24 425 Structure(s), see also Chain structure Chemical structures Cocontinuous structures Controlled structure Crystal structure Molecular structure Morphology Phase structure of carbon fibers, 26 737-739 detersive systems for, 8 413t HDPE, 20 157-162 LLDPE, 20 182-184, 203-205 polyesterether elastomer, 20 72-73 polyester fiber, 20 21 polyether antibiotics, 20 137-139 polyimide, 20 276-278 polymer, 20 395-405 protein, 20 449 PTT, 20 68t... 

The molecular structure of Te(S2COEt)(S2CNEt2) (262) is shown in Fig. 163 and it becomes immediately evident that the coordination geometry is the same as that found for the binary tellurium xanthates described above. The xanthate ligand forms Te—SI and Te—S bond distances of 2.535(2) and 2.911(3) A, respectively, and these are longer than the corresponding distances formed by the dithiocarbamate ligand of 2.489(3) and 2.801(3) A, respectively. This key... 

Figure 164. Two views of the molecular structure of the anion in fNEt4][Te(S2COMe)3] (a) showing the orthogonal relationship between the S5, S6 xanthate ligand and the remaining xanthate ligands and (b) highlighting the planar coordination about the tellurium atom.

The third diorganotellurium structure to be described has a chelating tellurium-bound organic group. In the molecular structure of [C6H4(CH2)2]Te(S2-COEt)2 (272), shown in Fig. 170, the two xanthate ligands form asymmetric... 

The preparation of 17o clearly showed that even stable compounds with lanthanide-tellurium bonds are easily accessible using this method. All three complexes exhibit strongly temperature-dependent HNMR spectra, which have been discussed in detail [47], The molecular structures of both 15o and 16o (Fig. 6) have been determined by X-ray diffraction [46, 47]. 

These guidelines for distinguishing between normal and iso compounds, developed for compounds in which the pseudo halo gens are bonded to carbon, might not be reliable when the pseudohalogens are bonded to the heavy tellurium atom. Molecular structures are not available for diorgano tellurium dipseudohalides. 

The existence of the tellurium analogue of S4N4 is unclear. It has long been known that explosive lemon-yellow nitride with the composition Tc3N4 (1) can be prepared. " While the molecular structure is not known, it is conceivable that it has a tricychc structure ... 

Fig. 2. Comparison of the molecular structures of the tellurium(IV) fluoride, chloride, and iodide types in the solid state. The selenium(IV) chlorides and bromides as well as tellurium(IV) bromide and one of the five forms of tellurium(lV) iodide are isostructural to the cubane-like Te4Cli6 molecules (244).

Fig. 6.14 (a) Molecular structure of /rans-teirachlorobis(tetramethylthiourea)tellurium(IV) in the monoclinic form. Note that the line Cl(4)—Te—Cl(2) approximates an axis for a pentagonal bipyramid if it is assumed that a lone pair occupies a position between S(l) and Cl(3) [Pg.120]

Brown and Crofts analyzed the microwave spectra of tellurophene for three isotopic constitutions of the molecule (C4H4l30Te, C4H4l28Te, C4H4126Te). The line frequencies, computed from the rotational constants obtained from least-squares fitting of low J transitions agree well with those observed. The constancy of the A rotational constant for the three isotopic species indicates that the tellurium atom is on the a axis. This, with the very small inertial defects, is consistent with a planar molecular structure of C2Ksymmetry. Stark shift measurements correspond to a dipole moment of 0.186 D. 

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. 

Figure 5. The molecular structure of [Ag3o(TePh)i2Te9(PEt3)i2] 3a. Tellurium atoms are represented as dark spheres and the silver atoms, with horizontal hatching, are labeled with numbers only for clarity. Tellurium atoms labeled Tel-Tel2 are the tellurolate ligands.

This family of compounds has been extensively studied in recent years. Wheeler has analyzed the electronic structure of Ni9(//4-Te)6(PEt3)8 with EH calculations. Hoffmann and coworkers have also used EH calculations to examine the electronic structure of this molecular cubic cluster to draw relationships with nickel-tellurium extended structures. More recently, we have performed EH and Xa calculations to rationalize the bonding in these clusters, as a function of different parameters such as the electron count or the nature and the size of the different elements constituting the cluster cage. " For symmetry reasons, a localized two-center-two-electron... 

The analogous dihydrogen derivatives of the heavier Group 16 elements are known. The molecular structures of HSSH and HSeSeH have been shown to be similar to that of HOOH, but the molecular structure of the tellurium analogue has not been determined. 

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