Tellurium Analogs

Ditellurimn analogs of phosphor-1,1-dithiolates and arseno-l,l-dithiolates are almost unknown. The only ditellurophosphinates reported are the hthium salts Li[R2PTe2] with R = Ph, cyclohexyl, obtained from R2PH with RLi followed by treatment with elemental tellurium in but telluroiminophosphinates, 

Scheithauer and R. Mayer, Thio- and dithiocarboxylic acids and their derivatives, in Topics in Sulfur Chemistry, A. Senning (ed), vol 4, Georg Thieme Publ., Stuttgart, 1979 (ft) E. Jansons, Usp. Khim., 1976, 45, 2030  

Haiduc, Supramolecular Organometallic Chemistry, Wiley-VCH, Weinheim, New York, 1999, p. 14 and 195. 

Kano and M. Kojima, Inorg. Chim. Acta., 2000, 311, 75. 

Zheng and H. Xiao, Syn. React. Inorg. Metal-org. Chem., 2004, 34, 1517. 

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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... 

Perfluoroalkyl)dibenzothiophenium salts and their selenium and tellurium analogs are novel perfluoroalkylating agents. The synthesis and reactivity of these compounds are covered by T. Umemoto (Ibaraki, Japan). Finally, the first detailed survey of the chemistry of 1,3-oxazinium and 3-azapyrylium salts for over twenty years is provided by S. Lukyanov (Rostov-on-Don, Russia). 

Iron-sulfur-nitrosyl complexes (continued) from tetranuclear precursors, 32 343 tellurium analogs, 32 350 tetrairon complexes, N NMR spectroscopy, 32 365 x-ray crystallography [Fe(NO)(S2CNR2)2 and related clusters, 32 359-361... 

FcjSRjCNO),], 32 355-358 heterometallics, 32 364 selenium analogs, 32 361-363 tellurium analogs, 32 361-363 Irradiation... 

The reaction of bis-phenylpropargyl ether (321) with tris(triphenylphosphine)rhodium chloride in benzene or toluene led to the formation of the unusual organometallic compound (322), which can be viewed as a derivative of an oxygen-rhodium pentalene system. Reaction of the rhodium complex (322) with sulfur leads to the corresponding 4,6-diphenyl-l,3-dihydro[3,4-c]furan (323). The selenium and tellurium analogs (324) and (325) were made in a similar manner (Scheme 111) (76LA1448). 

Other examples are [Rh2(CO)2(CsMes)2(/i-Te)] (186), reported by Herrmann (177) from the reaction between [Rh2(C5Me5)2(/i-CO)2] and elemental tellurium, which is assumed to contain a bent, two-coordinate tellurium analogous to that found in 164. Also known is the phosphine cobalt complex [Co2(PMe3)6(/i-Te)2] (187), prepared by Klein (178) from the reaction between the Zintl anion [SnTe4]4 and [CoCl(PMe3)3]. The tellurium... 

Even tellurium analogs of chromones and flavones have been prepared with Lawesson reagent280 (equation 35). 

The method employed earlier to obtain selenacoumarin (69BSB449) was also extended to the preparation of its tellurium analog 73.2-Methyltelluro-cinnamic acid was converted to its acyl chloride, which was cyclized to 73 in 20% yield under the action of A1C13 (84JHC1281). 

This strategy involving a Pummerer dehydration of sulfoxide and/or selenoxide is not applicable for preparation of tellurium analogs. The first diheteropentalene bearing the tellurolo[3,4-c]thiophene framework, e.g. 262, has been generated from 259 using tellurium metal in the presence of sodium iodide in DME. Compound 262 appears to be stable in dilute solution for no more than 1-2 h and adds to DMAD across the 4,6-positions in the tellurophene part. The intermediate 263 loses tellurium and collapses to a l,3,5,6-tetramethoxycarbonylbenzo[c]thiophene derivate 264 (Scheme 51) [81],... 

Such a structure is supported by the 19F-NMR spectrum (205) and has been confirmed more recently by electron diffraction for Se,0,FK and for the tellurium analog (207). 

Work by Smith and Cady in 1970 (209) showed strong evidence for the existence of Se2OFi0 and this was finally isolated by Reichert and Cady (213) and Seppelt (210) in 1972. Seppelt later prepared the tellurium analog (214 ). The selenium compound is prepared by fluorination of Se02 (213) or by thermal decomposition of Xe(OSeFr))2 at 130°C (210). Recent electron diffraction studies on the selenium and tellu-... 

In their 13C NMR spectra, the C-3 signals for 1,2-benzoselenazole (2) and its tellurium analog (3) appear at 5 160.7 and 168.3, respectively. This shift may be related to the decrease in electron-withdrawing activity in going from selenium to tellurium (78JHC865). 

Organotellurols 1, the tellurium analogs of alcohols, constitute a class of organic tellurium compounds, which have to be prepared and used in situ due to their high succeptibility to oxidation. The participation of this class of compounds in several reactions has been proposed,5-12 but their real existence has never been demonstrated in such processes. A few tellurols exhibiting special structural features could be isolated and characterized (e.g., compound 10, Figure 2).14... 

The ditellurium compounds, in which a Te —Te group joins two carbonyl groups, can be considered to be the tellurium analogs of peroxy compounds derived from carbonic acid or benzoic acids (e.g. benzoyl peroxides). Only a few of these compounds are known. During the reduction of aromatic nitro compounds with disodium telluride in dimethylfor-mamide, bis[dimethylaminocarbonyl] ditellurium was formed as a by-product in yields from 5 to 15%. The formation of this compound was attributed to the capture of the dimethylaminocarbonyl radical by the telluride anion and subsequent oxidation of the tellurocarbamoyl species4. 

Silanols and Siloxanes and Their Sulfiir, Selenium, and Tellurium Analogs... 

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