Selenocarbonyl complexes formation

The reactions of selenocarbonyl compounds with electrophiles are also well-established procedures. Alkylations or acylations of the selenium atom of selenoamides409 or selenoureas410 are known. Selenonium salts are formed initially they can then be converted into diselenides, selenazoles, or cyclic selenides depending on their structure. Reactions of selenocarbonyls with bromine and iodine have also been widely exploited. Selenocarbonates, sele-nothiocarbonates,411-415 and selenoureas416-418 can be employed, the reaction of 209 with 1 equiv. bromine led to the hypervalent 10-Se-3 complex 210, whereas an excess of bromine gave rise to a cleavage of the carbon-selenium double bond and formation of product 211 (Scheme 64). 

Alternatively, the reaction of isolated selenocarbonyl compounds with transition metal complexes has been applied to the synthesis of metal complexes of type 53. The complexation of furanselenoamides and thiopheneselenoamides to Pd, Rh, and Ru halides is accompanied with cyclometallization (Eq. 30) [111]. The formation of Cu [112a], Ag, Au [112b,c], Zn, Cd [113], Co [114], Cr, Mo, and W [115] complexes has been attained by reacting selenourea or selenoamides with the corresponding metal halides or metal carbonyls. 

---