Cyclic selenium imides

The chemistry of this interesting series of cyclic selenium imides, e.g., ligand behaviour, has not been investigated. 

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 77Se NMR spectra provide an informative analysis of the components of the reaction mixtures in these syntheses of cyclic selenium imides. The five- and... 

The 15-membered ring Se9(N Bu)6 (6.9) is a unique member of the series of cyclic chalcogen imides (see Section 12.8.1). It was first obtained as the major product of the reaction of LiN( Bu)SiMe3 with Se2Cl2 or SeOCl2. It is also formed, in addition to smaller cyclic selenium imides, in the cyclocondensation of SeCl2 with er -butylamine in THF or from the decomposition of the sele-nium(IV) diimide BuN=Se=N Bu. ... 

There are very few similarities between the cyclic selenium imides and their sulfur analogues (Section 12.6.1). The selenium imides that have been structurally characterised include examples of five-, six-, eight- and 15-membered rings cyclo-Se3(NR)2 (12.17, R = Bu, Ad), cyclo-Se3(N Bu)3 (12.18), cyclo-Se6(N Bu)2 (12.19) and cyclo-Se9(N Bu)6 (12.20). All of these derivatives have bulky alkyl substituents on the nitrogen atoms the parent selenium imides (R = H) are unknown. 

All studied model compounds can distinctly be divided into three groups (Table VII). The first group is composed of substances in which the sulfur, selenium or cyclopentadienyl anion acts as an anionic center. They exist only in open betaine forms, and their PES do not contain local minima corresponding to cyclic isomers. The second group contains compounds with arsonium cationic and oxide anionic centers and silicon and germanium betaines with arsonium and amide centers. They exist as cyclic isomers and their PES have no local minima corresponding to the open forms. Finally, the third group consists of six studied compounds with phosphonium cationic and oxide or amide anionic centers and arsonium-imide betaine. Their PES have minima for both cyclic and open forms separated by low barriers. 

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