Selenium complex anions

The unknown selenium-nitrogen anions [ScsN], [ScaNa] and [ScaNaH] have also been stabilized by coordination to platinum.A few examples of complexes involving anionic ligands with two different chalcogens, e.g., [ESNa] and [ESNaH] (E = Se, Te), are known. 

Complexes of the sulfenamido anion [RSNR ] with several transition metals [Zr(IV), Ti(IV), Mo(VI), W(Vf), Ni(If), and U(IV)] are known.They are prepared by the reaction of the lithium derivative of the sulfenamido anion with a metal halide complex. A selenium complex W(N Bu)2( BuNSePh)2 has been obtained in a similar... 

Schiff base complex, 32 13 -selenium complex FejScj complexes, 32 348 Fc4Se3 complexes, 32 349-350 Fc4Se4 complexes, 32 348-349 -selenium-nitrosyl complexes, 32 348-350 selenocyanates, 17 295, 296 sequestration in apoferritin, 36 463-464 silicates, Mbssbauer effect of, 6 474-479 -silicon compounds, 3 250 silyl complexes anionic tetracarbonyl, 25 37 binuclear carbonyls, 25 3, 5, 16, 33, 44-45, 116... 

The iodine is removed by adding a thiosulphate, and the selenium remains as a reddish-brown powder. Tellurites react under these conditions forming the complex anion, [Tel6]2, which also has a reddish-brown colour it is, however, decomposed and decolourized by a thiosulphate, thus permitting the detection of selenium in the presence of not too large an excess of tellurium. 

The preceding sections have shown that the behavior of the thiocyanate and selenocyanate groups in homogeneous complex anions is identical in both cases the nitrogen atom coordinates to the class a metal, and the sulfur or selenium atoms coordinate to the class b metal. Although fewer comparable cyanate complexes are known, it is quite clear that the coordination of the cyanate group is not governed by the same factors. 

Se-O bonds, 452 Se-P bonds, 452 Se-S bonds, 452 Se-Se bonds, 451 Se-Te bonds, 452 Selenium clusters/complexes anions, 1346 cations, 1341-1346 neutrals, 1341 Si-containing compounds C-H bonds, 100, 131, 133 C-O bonds, 344 N-C bonds, 418 N-H bonds, 377 O-H bonds, 261, 304 0-0 bonds, 315 Si-Br bonds, 465 Si-C bonds, 460-462 Si-Cl bonds, 464-465 Si-F bonds, 463 -464 Si-Ge bonds, 467 Si-H bonds, 455-459 Si-1 bonds, 465 Si-Mn bonds, 467 Si-N bonds, 463 Si-O bonds, 462-463 Si-P bonds, 466 Si-S bonds, 466 Si-Se bonds, 450,466 Si-Si bonds, 459-460 Si-Sn bonds, 467 Si-Te bonds, 466 Silicon neutral complexes anions, 1153 cations, 1147-1152 neutrals, 1140-1147 Sm-containing species neutrals, 623 -626 Sm clusters, 626 Sn-containing compounds 0-0 bonds, 315 Sn-Br bonds, 475-476 Sn-C bonds, 476-477 Sn-Cl bonds, 475 Sn-F bonds, 475 Sn-Ge bonds, 475 Sn-H bonds, 473-474 Sn-1 bonds, 476 Sn-O bonds, 477 Sn-Pb bonds, 475 Sn-S bonds, 477 Sn-Se bonds, 477 Sn-Si bonds, 467 Sn-Sn bonds, 474-475 Sn-Te bonds, 477 Sr-containing species neutrals, 591-593 Sr+ clusters, 593-595 Sulfates... 

While flame photometry could be used for the determination of complex anions containing metals (although for the most part anions are nuisances at best in this technique), the companion technique of atomic absorption has been applied to selenium by Rann and Hambly (22). They have determined selenium in the 10 to 100 p.p.m. range, using the 2040 A. 3S 3P transition and a propane-air flame. 

Cyclic selenium imides, e.g., Se7NH, are not available as a source of Se-N anions (Section 6.3). The only example of a metal complex of the [SesN] anion, Pt(Se3N)Cl(PMe2Ph), was obtained by the reaction of Sc4N4 with [PtCl2(PMe2Ph)]2. ... 

The first step consists in the attack of a proton on the W-H bond to yield a labile dihydrogen intermediate (Eq. (3)) that rapidly releases H2 to form a coordi-natively unsaturated complex (Eq. (4)). This complex adds water in the next step to form an aqua complex (Eq. (5)) that completes the reaction by substituting the coordinated water by the X anion (Eq. (6)). Steps (3)-(6) are repeated for each W-H bond and the factor of 3 in the rate constants appears as a consequence of the statistical kinetics at the three metal centers. The rate constants for both the initial attack by the acid (ki) and water attack to the coordinatively unsaturated intermediate (k2) are faster in the sulfur complex, whereas the substitution of coordinated water (k3) is faster for the selenium compound. 

There have been no reports of complexes of " JV-substituted thiosemicarbazones derived from 2-formylpyridine, but 2-acetylpyridine JV-methyl-thiosemicarbazone, 3a, formed [Fe(3a-H)2]C104 and [Fe(3a-H)2]FeCl4 [117]. The nature of these two species was established by partial elemental analyses, molar conductivities, magnetic moments, electronic, infrared, mass and electron spin resonance spectra. A crystal structure of a related selenosemicarbazone complex confirmed the presence of a distorted octahedral iron(III) cation coordinated by two deprotonated anions so that each ligand is essentially planar and the azomethine nitrogens are trans to each other the pyridyl nitrogen and selenium donors are both cis. 

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