Synthesis and structural study of bis-, tris- and tetra-[1,3,5]-dithiazinanyl silanes and stannanes

The synthesis and structural study of 23 new bis-, tris-, tetra-(dithiazinan-2-yl)silanes and stannanes is reported. The compounds were obtained by reaction of 5-alkyl-[1,3,5]-dithiazinanes (alkyl = Me, iPr, tBu) with tBuLi followed by addition of R′nSiCl4−n or R′nSnCl4−n (n = 0–2, R′ = Me and Ph) in THF. Structures were determined by 1H, 13C, 29Si or 119Sn NMR, mass spectrometry and X-ray diffraction analyses. Conformation of compounds in the solid state is discussed. The silanyl and stannanyl groups are in equatorial position in bis and tris-dithiazinanyl compounds in solution. The X-ray diffraction of tetra-(N-isopropyl-dithiazinan-2-yl)stannane showed that the tin atom is bound to two dithiazinanyl groups by equatorial bonds and to other two by axial bonds. Atomic distances indicate sulfur–silicon and sulfur–tin short contacts. NMR data, in particular 29Si and 119SN chemical shifts and 1J(13C, 119Sn) coupling constants, indicate the presence of weak S⋯Si and S⋯Sn interactions in the compounds. Ab-initio calculations were performed for (eq,eq,eq,eq), (ax,ax,ax,ax) and (eq,eq,ax,ax) conformers in order to find the most stable structures in tetra-(5-methyl-[1,3,5]-dithiazinan-2-yl)silane and tetra-(5-methyl-[1,3,5]-dithiazinan-2-yl)stannane.