Preparation of N(SeCl)2+X–(X = SbCl6 or FeCl4), F3CCSeNSeCCF3+SbCl6–, F3CCSeNSeCCF3, F3CCSeNSeCCF3 and F3CCSeSeC(CF3)C(CF3)SeSeCCF3. Electron diffraction study of F3CCSeSeCCF3 and crystal structure of the eight-membered heterocycle F3CCSeSeC(CF3)C(CF3)SeSeCCF3
The salts N(SeCl)2+SbCl6–1 and N(SeCl)2+FeCl4–2 were synthesized by reaction of SeCl3+ X–(X = SbCl6 or FeCl) with N(SiMe3)3; 1 was also formed by reaction of Se2NCl3 with SbCl5. Reaction of 1 with SnCl2 and F3CCCCF3 led to the formation of F3C[graphic omitted]CF3+ SbCl6–3. In this reaction the Se2N + cation is a likely intermediate because SnCl2 seems to be essential for chloride abstraction in the first reaction step to generate Se2N+in situ which then adds F3CCCCF3 to yield 3. Compound 3 is a useful building block to generate selenium compounds such as F3C[graphic omitted]CF34, F3C[graphic omitted]CF35 and F3C[graphic omitted]CF36. The heterocycle 5 was shown by electron diffraction to have an approximately planar four-membered ring structure. The structure of compound 6 was determined by X-ray crystallography: orthorhombic, space group Pbca, a= 10.1920(21), b= 13.0615(20) and c= 22.050(5)Å. In order to rationalize the structures of 5 and the cation F3C[graphic omitted]CF3+, ab initio calculations were made on model compounds in which the CF3 groups were replaced by a fluorine atom (i.e.F[graphic omitted]F for 5and F[graphic omitted]F+ for the cation in 3). In addition, mass spectrometric experiments were performed in order to examine the structures and stabilities of the unligated cation F3C[graphic omitted]CF3+ as well as its neutral counterpart. The existence of the neutral radical 4 was established by means of neutralization–reionization mass spectrometry.