Selenium thiolates

Metal-Sulfur, -Selenium, and -Tellurium Bond Lengths, M—E—C Angles, and Torsion Angles for Three-Coordinate Aluminum, Gallium, and Indium Thiolates, Selenolates and Tellurolates", and Related Compounds... 

Nickel-selenium coordination compounds have received attention in recent years, because a unique Ni-selenocysteine interaction was revealed in the active site of [FeNiSe]-hydrogenases.1083,1084 Of particular interest in this regard are mixed CO/selenolate complexes. Distorted square planar (393) was prepared from [CpNi(CO)]2, PhSeSePh, and [Fe(CO)3(SePh)3] and provides the first example of CO bound to a square planar Ni11 center in thiolate/selenolate environment.1085,1086 Upon addition of RSSR, species of the series [Ni(CO)(SR) (SePh)3 ] are formed. //(CO) ranges from 2,023 cm-1 to 2,043 cm-1 and is regarded as a spectroscopic reference for the CO binding site in [NiFeSe] hydrogenases. 

A number of zinc selenium complexes have now been characterized, with particular interest in the formation of zinc selenide semiconductors and quantum dots. In many cases analogous structures to those observed with thiol or thiolates are recorded. 77Se NMR is frequently used in characterization, and comparison with the sulfur equivalent is relevant. Zinc selenium compounds are of particular interest as precursors for metal/selenide materials and their relevance as models for selenocysteine-containing metalloproteins. 

According to this model the iron-hydride bond is cleaved upon illumination and the hydride, together with the proton, leaves the complex. This would lead to re-establishment of the nickel thiolate bond which was weakened in the former state, explaining the changes in the EPR spectrum observed after illumination (Pig. 7.16-III). After a flip of the electronic z-axis the selenium could in this state interact with the unpaired electron in an orbital with d -y2 character. To get EPR-active, CO-treated... 

Sulfur and Selenium Ligands. Many studies have been made on thiolates because of their relevance to natural Fe—S proteins (Section 17-E-10). Some are... 

The nucleophilicity of selenolates is significantly higher than that of the corresponding thiolates. This property allows selenolates to be useful reagents in organic synthesis. Moreover, removal of the selenium moiety from the reaction products is easier because the selenium - carbon bond is weaker than the sulfur-carbon bond [3 b]. 

The addition of alcohols to N-alkylidene selenoamides generated in situ leads to N-alkoxyalkyl selenoamides [84]. The substitution reaction of alkoxy groups of selenoesters [RC(Se)OR ] with aluminum thiolates or selenolates proceeds smoothly to give the corresponding esters [RC(Se)SR, RC(Se)SeR ] [7a, 85], whereas the addition of thiols to selenoaldehydes takes place at the selenium atom to afford selenenesulfides (RCH2SeSR ) [86]. 

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