Tellurium, elemental reactions with

The synthesis of the tellurium analogues of (24) and (25) requires a different approach, since it is not possible to prepare the necessary amido precursors in significant yields by telluration of [ BuN(H)P( U-N Bu)2PN(H) Bu]. However, the prior hthiation of this P(III)/P(III) system to give (7) followed by reaction with elemental tellurium generates the dianion (24, E = Te) as its dihthium salt (Eq. 5) [37] ... 

An interesting reaction with elemental tellurium (equation 182) was observed357. 

Heterocycle 108 was obtained in 45% yield by the reaction of dilithiated A-ethynylpyrrole 110 with elemental tellurium followed by a treatment of the reaction mixture with hexamethylphosphorus triamide [95JOM(493)271]. 

The only ditelluro-phosphorus acid reported to date is lithium dip-henylditellurophosphinate, [Ph2PTe2] Li+, prepared from the reaction of lithium diphenylphosphide with elemental tellurium (analogous to Equation 30).36,45... 

Sodium telluride and sodinm 0,0-diethyl phosphorotellurolate, prepared respectively by the Te/NaBH4DMF method and by the reaction of elemental tellurium with NaH and 0,0-diethyl phosphate in ethanol, react with arenediazonium fluoroborates, giving good yields of diaryl tellurides. ... 

The reaction of diarylmercurials with elemental tellurium under heating, one of the oldest methods for the preparation of diaryl tellurides, " has been later employed in some specific cases. " ... 

Reaction of elemental tellurium with arenediazonium salts ... 

The second approach to the preparation of 1-telluracyclohexane involves the reaction of 1,5-diiodopentane with elemental tellurium under heating (45JCS11). Initially formed (in 63% yield) 1,1-diiodo-l-telluracyclohexane 6 (X = I) is readily reduced to 1 by potassium metabisulfite in almost quantitative yield. 

The only known substituted tellurantrene is perfluorotellurantrene 101. Its adduct with two molecules of bromine, 5,5,10,10-tetrabromoperfluoro-tellurantrene, was isolated in 29% yield when o-diiodotetrafluorobenzene was allowed to react with elemental tellurium and then bromine was added to the reaction mixture (80JFC245). A subsequent reduction with sodium sulfide affords 101 in rather low 20% yield, unusual for the typically smooth reduction of cr-telluranes. 

The reaction of enol phosphates 84 with lithium -butyl tellurolate 85a, generated by reaction of -butyllithium with elemental tellurium, occurs rapidly to give the corresponding vinylic tellurides 86 (Scheme 51). Mixtures of (Z)- and ( )-enol phosphates afford the (Z)-vinylic telluride as the only product. ... 

The insertion of elemental tellurium into C — Li or C — Na bonds is a convenient method for the preparation of alkali metal tellurolates. Many organic lithium compounds are commercially available or can be prepared, for instance, by halogen-lithium or hydrogen-lithium exchange. The reactions of the organic lithium compounds with elemental tellurium are performed in inert organic solvents such as diethyl other, tetrahydrofuran, tetrahydrofuran/hexane, or diethyl ether/benzene at temperatures (— 196° to + 20°) compatible with the stability of the organic lithium compound. The applicability of this reaction for the synthesis of aliphatic, aromatic, and heteroaromatic lithium tellurolates is documented in Table 1 (p. 155). 

The reaction of elemental tellurium with cesium 3-cow io-3-cobaltabis[decahydro-l,2-dicarba-c/o.vo-dodecaborate] in acetic anhydride/sulfuric acid and the methylation of the resulting product with dimethyl sulfate produced 8,8 -methylielluro-3-commo-3-cobaltabis[l,2-dicarba-closo-dodecaborane in low yield3. 

That the nature of the polytelluride solution plays an important role is also borne out by studies of the chromium-telluride system. If the polytel-lurides are prepared in situ by the reaction of elemental potassium with elemental tellurium in DMF, the products are considerably cleaner and can be obtained in higher yields than when the polytelluride source is a premade potassium salt, such as K2Te2 or K2Te3, It has been suggested that equilibria are occurring in the reaction flask. Pure Te2- and Te2- can be prepared in pure form in liquid ammonia, but there is no evidence for the formation of higher tellurides in the presence of alkali metal counter-... 

A nucleophilic metal anion has been used as a reducing agent to create Zintl ion directly. [PPN]2[Fe2(CO)6(Te2)2] (169) has been synthesized by direct reaction of Na2[Fe(CO)4] with elemental tellurium.115 Although not structurally characterized by X-ray methods, the formulation of 169 is supported by several pieces of experimental evidence. It can react with itself or with the Zintl ions present to produce mixed-metal species. It reacts with iodomethane to yield [Fe2(CO)6(/z-TeMe)2] (170) (Fig. 56),... 

W(PMe3)4(H)2(SH)2] could also be detected. Reaction of the dUiydride [WH2(PMe3)4] with elemental tellurium afforded [WH2(PMe3)4(/c -Te2)2], from which [W(Te)2(PMe3)4] could be obtained by oxidative cleavage of the Te-Te bonds. 

The osmium carbyne complex 115 reacts with elemental sulfur, selenium, and tellurium to afford the complexes 135 in which the element atoms "bridge the metal-carbon triple bond [Eq. (123)] (56). Complex 115 also reacts with transition metal Lewis acids such as AgCl or Cul to give dinuclear compounds with bridging carbyne ligands. Reaction with elemental chlorine results in addition across the metal-carbon triple bond to generate the chlorocarbene osmium complex 136 [Eq. (124)]. 

The oxidation of 2a with elemental sulfur and tellurium quantitatively furnish the three-membered heterocycles 15 and 16, respectively. The latter do not yield l,3-dichalcogen-2,4-phosphasila-cyclobutanes on treatment with excess elemental sulfur or tellurium. The reaction of 6 and 7 with elemental tellurium furnished a 1 1 mixture of the diasteromeres 17a,b and 17c,d (/-butyl/Si(/Pr)3 m-and /rans-forms), respectively, which were characterized by means of NMR spectroscopy ( P, Si, Te) [12, 19]. 

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