title: 5,6,7,8-Tetrafluoro-3lambda4delta2,1,2,4-benzothiaselenadiazine, 5,6,7,8-tetrafluoro-1,3lambda4delta2,2,4-benzodithiadiazine, and their hydrocarbon analogues: molecular and crystal structures.
abstract: 5,6,7,8-Tetrafluoro-3lambda4delta2,1,2,4-benzothiaselenadiazine (1) is prepared by the intramolecular nucleophilic cyclization of C6F5SeN=S=NSiMe3 (2) mediated by CsF. According to an X-ray diffraction analysis, the heterocycle of 1 is bent along the Se(1)...N4 line by 6.0(2) degrees in the crystal. Despite the obvious similarities between 1 and its 1,3-dithia analogue (7) with respect to molecular composition and shape, the crystal packing of 1 is substantially different from that of 7. An interesting consequence of this is the inclusion of atmospheric N2 in the crystal lattice of the selenium derivative 1. The molecular structure and bonding of 1 have been investigated using quantum-chemical calculations at the DFT/B3LYP/6-311+G level of theory, and the results have been compared to those of 5,6,7,8-tetrafluoro-1,3lambda4delta2,2,4-benzodithiadiazine (7) and their hydrocarbon analogues (5 and 8).
authors.affiliation: Institute of Organic Chemistry, Russian Academy of Sciences, 630090 Novosibirsk, Russia.
authors.forename: Alexander Yu
authors.initials: AY
authors.lastname: Makarov
authors.forename: Karla
authors.initials: K
authors.lastname: Tersago
authors.forename: Kanda
authors.initials: K
authors.lastname: Nivesanond
authors.forename: Frank
authors.initials: F
authors.lastname: Blockhuys
authors.forename: Christian
authors.initials: C
authors.lastname: Van Alsenoy
authors.forename: Mikhail K
authors.initials: MK
authors.lastname: Kovalev
authors.forename: Irina Yu
authors.initials: IY
authors.lastname: Bagryanskaya
authors.forename: Yuri V
authors.initials: YV
authors.lastname: Gatilov
authors.forename: Makhmut M
authors.initials: MM
authors.lastname: Shakirov
authors.forename: Andrey V
authors.initials: AV
authors.lastname: Zibarev