Sulfur tellurium analogs

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... 

Thiols and sulfides are occasionally prepared by treatment of Grignard reagents with sulfur.318 Analogous reactions are known for selenium and tellurium compounds. Grignard reagents... 

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). 

On the other hand, Rudin et al. [192] found theoretically a progression j8-Po— simple cubic (sc)—>fccc instead of the previously expected P-Po—>bcc transition for sulfur by analogy with selenium and tellurium. In addition, the face-centered cubic (fee) structure of Se (and Te) stable at pressures... 

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

Table 17.2 shows the formulas of the catenated sulfur oxoacids and one resonance structure for each corresponding anion. Note from the table that not all these acids exist in the free state, but all the anions are well-known. None of these acids or anions have selenium or tellurium analogs in which aU the sulfur atoms are replaced by a heavier congener. 

In the following equations, selenium and tellurium exhibit behavior that is analogous to that of sulfur ... 

Phenylchalcogenyl-l-naphthols with sulfur (91), selenium (92), and tellurium (93) were prepared, as was the methylene analog (90), and their oxidation potentials determined by CV vs. SCE. All were irreversible, and only the Te compound 93 (1.00 V) differed significantly from the other three ( 1.25 V) (Table 9). It is likely that the naphthol moiety is controlling the oxidation potential of 90-92. Interestingly, only 93 showed significant ability to inhibit lipid peroxidation in a... 

The brown material, insoluble in water, examined more carefully [said he], was recognized to be the cause of the peculiar odor we mentioned above and by means of some experiments which we shall report soon, it was found that it was a combustible, elementary substance hitherto unknown, to which I have given the name selenium, derived from Selene (the moon), to recall its analogy with tellurium. According to its chemical properties, this substance belongs between sulfur and tellurium, although it has more properties in common with sulfur than with tellurium (9,17). 

Selenium-bismuth bonds are formed in the mutual cleavages of dibismuthines and diselenides (equation 69).218 This particular compound is stable at -30 °C, unlike the tellurium analogue. At room temperature the compound disproportionates to give the diseleno derivative (equation 70). Similar behaviour was noted in the analogous sulfur compounds (Section 28.17.2.1). 

Trialkyl cations of oxygen, sulfur, and selenenium (and less commonly tellurium) are onium ions by virtue of their having one extra valence, although these three-coordinate ions invite comparison with carbenium ions. These ions (e.g., 28, 29, and 30) are not planar (as opposed to the analogous carbenium ions), but rather are pyramidal. These species have a well-characterized solution acid chemistry concentrated sulfuric acid is required for observation of the trimethyloxonium cation, but the sulfonium and selenonium ions require less strongly acidic solutions. 

The number of iron-selenium-nitrosyl complexes is substantially smaller than the iron-sulfur-nitrosyl species, as considerably less work in this area has been reported. However there are a number of differences between the sulfur systems and their analogs containing selenium or tellurium. For selenium it is convenient to divide the complexes into three classes, dependent upon the stoichiometry of the metal-chalcogen framework. 

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