Selenium-bridged

Selenylation can also be done under conditions in which another nucleophilic component of the reaction captures the selenium-bridged ion. For... 

Oxidation of the sulfur- or selenium-bridged azepines (171 X=S or Se) with mercury(II) oxide in methanol yields ultimately the 4f/-azepine (68JCS(C)23ll) with hydrogen peroxide as oxidant, the sulfur compound furnishes the sulfoxide (171 X=SO). Selenium dioxide oxidation of 7,8-dimethyl-lf/-l-benzazepin-2-one affords the 2,3-dioxo derivative (173) that displays no evidence of enol tautomers or heteroaromaticity (7ici(L)1439). 

YbSe". With (Me3Si)2N]3M (M = La, Ce) and (Me3Si)SiSeH, 3-coordinate monomers result in toluene but the Y derivative occurs in solution as a selenium bridged dimer. The La, Sm and Yb(III) derivatives complex with 2 moles of THF100. 

In contrast to thionyl chloride, which is used frequently as a reagent in synthesis, the applications of seleninyl chloride (SeOCl2) are very limited. It can be used to synthesize selenium-bridged chromanones332 or in the synthesis of novel selenium-containing heterocycles.333 334... 

In contrast to thionyl chloride, which is commonly used as a reagent in organic synthesis, the application of seleninyl chloride (112) is limited to a few reactions. Thus, the new selenium-bridged chromanones 113 were prepared by the condensation of this chloride with enaminones of the 2-hydroxy-phenylethanone type 114 [57] (Eq. 24). 

Reaction of diaminocyclopropeneselones with diaminochlorocyclopropenylium salts in acetonitrile afforded selenium bridged dications 2. ... 

The synthetic routes to the limited number of tri- and tetra-dentate ligands containing selenium, which, with the exception of an open chain tetraselenoether, are of the hybrid type incorporating nitrogen or phosphorus donors, have been recently reviewed. The tetradentate selenoether, bsep, has been shown to react with Na2PdX4 (X = Cl, Br or I) to give Pd2(bsep)X4 which, on the basis of IR spectroscopy, have been formulated as selenium-bridged dimers (4). 

Ethanethio-derivatives of C-nucleosides (and anhydro-nucleoside analogues containing selenium bridges) are described in Chapter 19. 

Studies on the selenium>bridged compound (CF8)2P-Se P(CF8)2 were dealt with earlier (see pp. 2S4,255). 

Liu, Y. Li, L., Fan. Z. Zhang. H.-Y. Wu, X. Guan, X.-D. Liu, S.-X. Supramolecular aggregates formed by intermolecular inclusion complexation of organo-selenium bridged bis(cyclodextrin)s with calyx[4]arene derivative. Nano Lett. 2002, 2. 257-261. 

The copper atoms in the vast majority of the clusters can be assigned a formal charge of +1, while the chalcogen ligands are formally viewed as E or RE groups. Some of the selenium-bridged species, however - and nearly all copper telluride clusters - form nonstoichiometric compounds that display mixed valence metal centers in the formal oxidation states 0 and +I or +I and +11. These observations correlate with those made for the binary phases CU2S, Cu2 xSe, and Cu2- Te [38-40]. 

Selenium-Bridged Copper Clusters The reactions yielding all PR2R -coated selenium-bridged copper clusters that have been isolated and structurally characterized to date, in order of increasing cluster size, are summarized in Scheme 3.4. 

Scheme 3.4 Survey of the synthesis of selenium-bridged copper clusters protected by terminal phosphine ligands.

In the case of selenium-bridged copper clusters, it was found that there is a structural transition from molecular spherical structures towards cutouts of the bulk structure when the clusters reach 70 copper atoms. An analogous structural transformation has not yet been found in the case of sulfur-bridged silver clusters. For etample, the dication [Ag7oS2o(SPh)28(dppm)2o] in 94 shows a sheD-like sulfur substructure that consists of an inner Sg and an outer S40 polyhedron (Figure 3.73). 

Selenium-Bridged Silver Clusters The reaction chemistry of Ag(I) and... 

Optical Spectra of Selenium-Bridged and Tellurium-Bridged Copper Clusters... 

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