Te Bonds Research Articles

“Piano‐Stool” Complexes of Ruthenium(II) Designed with Arenes and N‐[2‐(Arylchalcogeno)ethyl]morpholines: Highly Active Catalysts for the Oxidation of Alcohols with N‐Methylmorpholine N‐Oxide, tert‐Butyl Hydroperoxide and Sodium Periodate and Oxychloride

AbstractThe reactions of [{(η6‐C6H6)RuCl(μ‐Cl)}2] and [{(η6‐p‐cymene)RuCl(μ‐Cl)}2] with N‐[2‐(arylchalcogeno)ethyl]morpholines (L) (aryl = Ph/2‐pyridyl for S, Ph for Se, 4‐MeOC6H4 for Te) and NH4PF6 result in “piano‐stool” complexes of RuII of composition [RuCl(η6‐C6H6)(L)][PF6]/[RuCl(η6‐p‐cymene)(L)][PF6], which give characteristic 1H, 13C{1H}, 77Se{1H}, and 125Te{1H} NMR spectra. Some of them have also been characterized by X‐ray crystallography [Ru–S, Ru–Se, and Ru–Te bond lengths: 2.3815(12)/2.3742(14), 2.4837(14), and 2.6143(7) Å, respectively]. The cyclic voltammograms show that all the complexes undergo irreversible oxidation (E${1 \over 2}$ = 0.290–0.586 V). All the ruthenium complexes have been explored for their catalytic activity in the oxidation of primary and secondary alcohols with N‐methylmorpholine N‐oxide (NMO), tBuOOH, NaOCl, and NaIO4 (TON values upto 9.8 × 104). The efficiency of the catalytic oxidation reaction decreases in the order Te > Se > S. The intermediate species involved in the oxidation reactions appear to incorporate the RuIV=O group.

ChemInform Abstract: Ternary and Quaternary Uranium and Thorium Chalcogenides

A survey of the structural chemistry of ternary and quaternary uranium (U) and thorium (Th) chalcogenides is presented. Specific attention is paid to the coordination environments of U and Th in a variety of classical and nonclassical structure types. The problems of defining the oxidation state of U from U-Q (Q = S, Se, Te) bond lengths and magnetic susceptibility data are also discussed.

ChemInform Abstract: [Mn(en)3]CdSnTe4 and [Mn(en)3]Ag6Sn2Te8: New Intermetallic Tellurides Synthesized in Superheated Organic Medium.

Two intermetallic tellurides, Mn(en)3]CdSnTe4 (I) and [Mn(en)3]Ag6Sn2Te8 (II), have been synthesized in superheated ethylenediamine solutions at 180 °C. Single-crystal X-ray diffraction analyses show that I crystallizes in triclinic crystal system, space group P1 (No. 1) with lattice parameters a = 9.134(2) A, b = 10.085(3) A, c = 12.691(3) A, α = 73.52(2)°, β = 86.05(2)°, γ = 76.43(2)°, V = 1089.7(5) A3, and Z = 2 and II belongs to trigonal (rhombohedral) crystal system, space group R3m (No. 166) with a = 8.9590(9) A, c = 34.795(2) A, V = 2418.6(4) A3, and Z = 3. Both compounds possess new structure types. The structure of I is composed of one-dimensional Zintl chains of alternating edge-sharing MTe4 (M = Cd, Sn) tetrahedra and [Mn(en)3]2+ complex cations that are between the chains. The structure of II contains two-dimensional double layers of Ag6Sn2Te82- formed by connecting two single honeycomb-like layers through M−Te bonds (M = Ag, Sn). The double layers are separated by the [Mn(en)3]2+ templates. ...

Electronic structure of the thermoelectric materials PbTe and AgPb18SbTe20 from first-principles calculations

To investigate the effects of substituting Ag and Sb for Pb on the thermoelectric properties of PbTe, the electronic structures of PbTe and AgPb18SbTe20 were calculated by using the linearized augmented plane wave based on the density-functional theory of the first principles. By comparing the differences in the band structure, the partial density of states (PDOS), the scanning transmission microscope, and the electron density difference for PbTe and AgPb18SbTe20, we explained the reason from the aspect of electronic structures why the thermoelectric properties of AgPb18SbTe20 could be improved significantly. Our results suggest that the excellent thermoelectric properties of AgPb18SbTe20 should be attributed in part to the narrowing of its band gap, band structure anisotropy, the much extrema and large DOS near Fermi energy, as well as the large effective mass of electrons. Moreover, the complex bonding behaviors for which the strong bonds and the weak bonds are coexisted, and the electrovalence and covalence of Pb–Te bond are mixed should also play an important role in the enhancement of the thermoelectric properties of the AgPb18SbTe20.

Correction: Chemistry and Physical Properties of the Phosphide Telluride Zr2PTe2

The ICOHP values for the Zr–P and Zr–Te bonds reported on page 3107 (2nd column)1 should be multiplied by 3 and the value for the Zr–Zr bond by 9. Therefore, the correct values read: 2.420, 1.770 and 0.369 eV bond1 for Zr–P, Zr–Te and Zr–Zr, respectively. However, this correction does not influence the discussion made in the text. The Authors

Local atomic structure of superconductingFeSe1−xTex

The isovalent substitution of Te for Se in the superconducting $\ensuremath{\alpha}\text{-FeSe}$ raises ${T}_{C}$ where the average chalcogen--Fe bond angle decreases and the chalcogen-Fe distance increases. Locally, however, the Se and Te ions do not share the same site and have two distinct $z$ coordinates, in contrast to what is presumed in the $P4/nmm$ symmetry. The local bond angle between the chalcogens and Fe increases with the substitution, consistent with the rise in ${T}_{C}$, the Fe--Te bonds become shorter than in the binary FeTe, while the Fe--Se bonds stay the same as in the binary. Ab initio calculations based on spin density functional theory yielded an optimized structure with distinct $z$ coordinates for Se and Te, in addition to a stronger hybridization of Te with Fe.

T c = 21 K in epitaxial FeSe0.5Te0.5 thin films with biaxial compressive strain

Epitaxial FeSe0.5Te0.5 thin films with different thickness were grown by pulsed laser ablation deposition on different substrates. High purity phase and fully epitaxial growth were obtained. By varying the film thickness, superconducting transition temperatures up to 21 K were observed, significantly larger than the bulk value 16.2 K. Structural analyses indicated that the c-axis is smaller than the bulk value but it is almost independent of the film thickness and the a-axis changes significantly with the film thickness and is linearly related to the Tc. The latter result indicates the important role of the compressive strain in enhancing Tc. Tc is also related to both the Fe–(Se,Te) bond length and angle, suggesting the possibility of further enhancement.

Synthesis and structural features of new aryltellurenyl iodides

(TmpTe) 2 (tmp = 2,3,5,6-tetramethylphenyl) reacts with I 2 to yield the sterically stabilized arenetellurenyl iodide [tmpTeI] 2 ( 1). The reaction of 1 with I 2 gives [tmpTe(I)I 2] ( 2), which formally results from the association of the intermediary RTeI with I 2 under oxidation to Te III. Compound 1 reacts also with (PyH)I to give the hypervalent, 3c−4e, T-shaped complex (PyH)[tmpTeI 2] ( 3). The reaction of 3 with I 2 gives (PyH)[tmpTeI 3(I 3)] ( 4), a rare example of Te IV compound in which a I 3 - chain appears as component of the complex and not as solvate. Complex 3 reacts also with I 2 in the presence of water with hydrolysis of the R−Te bond, leading to the structurally rare compounds (PyH) 2[TeI 4(μ-I) 2TeI 4] ( 5), [(tmp) 2TeI 2] ( 6) and (PyH) 2[TeI 6]·I 2 ( 7). The structural features of the products are discussed, as well as the synthetic procedures.

The crystal structure of [formula omitted

The crystal structure of the superconductor FeSe 0.44 Te 0.56 was redetermined by high-resolution X-ray single crystal diffraction at 173 K (anti-PbO-type, P 4 / n m m , a = 3.7996 ( 2 ) , c = 5.9895 ( 6 ) Å, R 1 = 0.022 , w R 2 = 0.041 , 173 F 2 ). Significantly different z -coordinates of tellurium and selenium at the 2 c site are clearly discernible and were refined to z Te = 0.2868 ( 3 ) and z Se = 0.2468 ( 7 ) . Thus the chalcogen heights differ by 0.24 Å and the Fe–Se bonds are by 0.154 Å shorter than the Fe–Te bonds, while three independent (Te, Se)–Fe–(Te, Se) bond angles occur. An elevated U 33 displacement parameter of the iron atom is suggestive of a slightly puckered Fe layer resulting from different combinations of Se or Te neighbors. Such strong disorder underlines the robustness of superconductivity against structural randomness and has not yet been considered in theoretical studies of this system.

Palladium and half sandwich ruthenium(II) complexes of selenated and tellurated benzotriazoles: Synthesis, structural aspects and catalytic applications

1-(Phenylselenomethyl)-1 H-benzotriazole ( L 1 ) and 1-(4-methoxyphenyltelluromethyl)-1 H-benzotriazole ( L 2 ) have been synthesized by reacting 1-(chloromethyl)-1H-benzotriazole with in situ generated nucleophiles PhSe − and ArTe −, respectively. The complexes of L 1 and L 2 with Pd(II) and Ru(II)(η 6- p-cymene) have been synthesized. Proton, carbon-13, Se-77 and/or Te-125 NMR spectra authenticate both the ligands and their complexes. The single crystal structures of L 1 , L 2 and [RuCl(η 6- p-cymene)( L)][PF 6] ( L = L 1 : 3, L = L 2 : 4) have been solved. The Ru–Se and Ru–Te bond lengths have been found 2.4801(11) and 2.6183(10) Å, respectively. The palladium complexes, [PdCl 2( L)] ( L = L 1 : 1, L = L 2 : 2) have been explored for Heck and Suzuki–Miyaura C–C coupling reactions. The TON values are upto 95,000. The Ru-complexes have been found promising for catalytic oxidation of alcohols (TON ∼ 7.8–9.4 × 10 4). The complexes of telluroether ligands are as efficient catalysts as those of selenoether ones and in fact better for catalytic oxidation.

Ge40.0Te5.3I8: synthesis, crystal structure, and properties of a new clathrate-I compound

A new clathrate phase with the composition Ge40.0Te 5.3I8 has been prepared and its structure deter- mined from single crystal X-ray data. It crystallizes in the cubic space group Pm3n with a unit cell parameter a ¼ 10.815(1) � and Z ¼ 1( R ¼ 0.031 for 272 indepen- dent reflections and 19 variables). Germanium and tellur- ium form a cationic clathrate framework hosting the guest iodine anions in cages of two different shapes. The catio- nic framework features a joint occupation on two of the three independent sites by germanium and tellurium, lead- ing to the formation of Ge- -Ge and Ge- -Te bonds and vacancies on the third position. Electron diffraction and high-resolution electron microscopy reveal that the bulk material is not uniform; it contains domains showing a tendency for segregation of tellurium and germanium within the 4-fold positions of the space group P23, which is a subgroup of Pm3n .G e 40.0Te 5.3I8 is a diamagnetic semiconductor with a band gap of about 0.8 eV and its composition agrees with the Zintl formalism for the charge-balanced compounds.

The structure of As 3Se 5Te 2 infrared optical glass

The structure of As 3Se 5Te 2 infrared optical glass was investigated by X-ray and neutron diffraction as well as extended X-ray absorption fine structure measurements at the As-, Se- and Te K-edges. The five datasets were modelled simultaneously by the reverse Monte Carlo simulation technique. Experimental data could be fitted satisfactorily by allowing As–Se, As–Te and Se–Te bonds only. It was revealed that the affinity of As is much higher to Se than to Te. The nearest As–Se distance is similar to that found in other vitreous As–Se based alloys, while the As–Te bond length is 0.02–0.04 Å shorter in As 3Se 5Te 2 than in binary As–Te glasses.

Preparation of TeO 2 based thin films by nonhydrolytic sol–gel process

To solve the problem of the extremely high hydrolytic reactivity of tellurium alkoxides in hydrolytic sol–gel method, the nonhydrolytic sol–gel process has been applied as a novel route for producing TeO 2 based thin films. The transition of nonhydrolytic sol–gel was monitored by means of 1H NMR, FT-IR and Raman techniques. These results show that the formation of Te–O–Te bonds in gel networks mainly resulted from the nonhydrolytic cross-condensation reaction between different Te–OR groups. The decomposition process and structure evolution of the nonhydrolytic gel products were investigated and managed. Results from DTA and XRD analyses show that metallic tellurium, β-TeO 2 and α-TeO 2 phase appeared in the film during heat-treatment process at around 300, 350 and 400 °C, respectively. The formation of metallic tellurium can be alleviated through preheating the gel films under O 2 atmosphere or by additions of the second component. Crystallization of α-TeO 2 could be retarded by additions of TiO 2 or Al 2O 3, and the transparent, homogeneous amorphous TeO 2 based thin films were obtained by the methods above. The nonhydrolytic sol–gel process developed in this study offers a simple and practical method for fabricating TeO 2 based thin film devices.

Relationship between Structure and Superconductivity in FeSe1-xTex

We determined the crystal structural parameters of FeSe 1- x Te x ( x =0.5, 0.625, 0.75, 0.875) and FeSe by using the neutron powder diffraction technique. It was found that the superconducting transition temperature T c of FeSe 1- x Te x increased with the (Se,Te)–Fe–(Se,Te) bond angle α in the Te-doped samples. However, T c of FeSe did not exhibit a similar relation. In order to explain this contradiction, we studied the temperature dependence of the z position of chalcogens, which is strongly coupled to the spin fluctuation by theoretical calculations. The z position in FeSe showed a remarkable shift, indicating that strong spin fluctuation can affect the superconductivity in FeSe.

Phase change behavior in oxygen-incorporated Ge2Sb2Te5 films

Oxygen-incorporated Ge2Sb2Te5 (GST) films were deposited using ion beam sputtering deposition. Sheet resistance in films with 16.7% oxygen content decreased at a higher annealing temperature than that of undoped GST films, while resistance in films with an oxygen content of over 21.7% decreased dramatically at lower temperatures. X-ray diffraction patterns showed crystallization to face-centered cubic phase was suppressed. However, phase separation to a hexagonal structure was observed in films with an oxygen content of over 21.7%. Extended x-ray absorption fine structure data of Ge K edge showed Ge was bonded to O as well as Te. Moreover, a stoichiometric GeO2 phase was not observed, while phase separation into Sb2O3 and Sb2Te3 occurred. The results indicate Ge–Te bonds with oxygen are related to structural stability.

A composition dependent thermal behavior of GexSe35−xTe65 glasses

Abstract Alternating differential scanning calorimetric (ADSC) studies have been performed to understand the thermal behavior of bulk Ge x Se 35− x Te 65 glasses (17 ⩽ x ⩽ 25); it is found that the glasses with x ⩽ 20 exhibit two crystallization exotherms ( T c1 & T c2 ). On the other hand, those with x ⩾ 20.5, show a single crystallization reaction upon heating. The exothermic reaction at T c1 has been found to correspond to the partial crystallization of the glass into hexagonal Te and the reaction at T c2 is associated with the additional crystallization of rhombohedral Ge Te phase. The glass transition temperature of Ge x Se 35− x Te 65 glasses is found to show a linear but not-steep increase, indicating a progressive, but a gradual increase in network connectivity with Ge addition. It is also found that T c1 of Ge x Se 35− x Te 65 glasses with x ⩽ 20, increases progressively with Ge content and eventually merges with T c2 at x ≈ 20.5 (〈 r 〉 = 2.41); this behavior has been understood on the basis of the reduction in Te Te bonds of lower energy and increase in Ge Te bonds of higher energy, with increasing Ge content. Apart from the interesting composition dependent crystallization, an anomalous melting behavior is also exhibited by the Ge x Se 35− x Te 65 glasses.

Vibrational properties of hexagonalGe2Sb2Te5 from first principles

Phonons at the Γ point and the Raman spectrum of the hexagonalGe2Sb2Te5 were computed within density functional perturbation theory. The three different stackingsof the Ge/Sb planes proposed in the experimental literature were considered. Thetheoretical Raman spectrum is similar for the three stackings with a marginallybetter agreement with experiments for the structure proposed by Matsunagaet al (2004 Acta Crystallogr. B 60 685) which assumes a disorder in Ge/Sb siteoccupation. Although the large broadening of the experimental Raman peaks preventsdiscriminating among the different stackings, the assignment of the Raman peaksto specific phonons is possible because the main features of the spectrum arerather insensitive to the actual distribution of atoms in the Sb/Ge sublattices.On the basis of the energetics (including configurational entropy) two stackingsseem plausible candidates for GST, but only the mixed stacking by Matsunaga et al reproduces the spread of Ge/Sb–Te bond lengths measured experimentally.

Synthesis and X-ray investigation of novel Fe and Mn phenyltellurenyl-halide complexes: (CO)3FeBr2(PhTeBr), (η5-C5H5)Fe(CO)2(PhTeI2) and CpMn(CO)2(PhTeI)

Abstract New complexes of transition metals with organotellurium halide ligands are reported. Iodination of [CpMn(CO)2]2(μ-Ph2Te2) leads to the Te–Te bond cleavage and formation of CpMn(CO)2(PhTeI). Oxidative addition of PhTeBr3 to Fe(CO)5 gives the monomeric complex (CO)3FeBr2(PhTeBr) which is isostructural with the recently reported (CO)3FeI2(PhTeI). Insertion of phenyltellurenyl iodide (PhTeI) into the Fe–I bond of CpFe(CO)2I forms CpFe(CO)2(TeI2Ph). Molecular structures of the reported complexes were determined by single-crystal X-ray diffraction analysis (XRD). A considerable shortening of metal–tellurium distances is observed.

Organotellurium-Mediated Controlled/Living Radical Polymerization Initiated by Direct C−Te Bond Photolysis

UV-vis irradiation of an organotellurium chain transfer agent in the presence of vinyl monomers leads to the formation of highly controlled living polymers with predetermined number average molecular weights and narrow molecular weight distributions.

Gold complexes of ditelluridoimidodiphosphinate ligands — Reversible oxidation of Au(I) to Au(III) via insertion of gold into a phosphorus–tellurium bond

The reaction of (THT)AuCl with (TMEDA)Na[N(TePR2)2] (R = Ph, i-Pr, t-Bu) produces a series of gold (III) complexes of the type [{R2PNP(Te)R2}Au(µ-Te)]2 (4a, R = i-Pr; 4b, R = Ph; 4c, R = t-Bu) rather than the expected homoleptic Au(I) complexes of the ditelluridoimidodiphosphinate ligands. A combination of solution- and solid-state NMR studies shows that both cis and trans isomers of 4a–4c are formed in these reactions. X-ray structural determinations of the trans isomers of 4a–4c reveal a centrosymmetric arrangement with a central four-membered Au2Te2 ring formed by the formal insertion of gold into a P–Te bond; this insertion process was shown to be reversible upon addition of PPh3 to 4a to give the monomeric gold(I) complex Ph3PAu[N{TeP(i-Pr)2}2]. The X-ray structure of cis-4b is also described.Key words: gold, tellurium, redox, X-ray structures, imidodiphosphinate.