Synthesis and Thermal Investigations of Eleven-Membered Ring Systems Containing One of the Heavier Group 14 Element Atoms Si, Ge, and Sn

Abstract

Unique eleven-membered rings containing silicon, germanium, and tin were synthesized in good yields by the reactions of the corresponding 1,2-bis((2-bromothiophen-3-yl)methoxy)benzenes with (C6H5)2ECl2 where E = Sn, Ge, Si. The Sn and Ge congeners were crystallized, but the conformers that these rings crystallized in, were quite different. As confirmed by Density Functional Theory (DFT) calculations, (C28H22O2S2Sn) assumes a unique crystal structure that leaves more room around the tetrel atom as compared to the crystal structure of the corresponding Ge compound. In the latter, the central cavity is quite open, whereas in the former, one of the methylene groups can fold inwards. Another consequence is the influence on the planes of the aromatic rings flanking the heterocycle. In the Ge case, the benzene ring is folded away from the central cavity, whereas in the Sn case, it is almost parallel to the imaginary axis through the center of the ring. Thermal analysis investigations (TGA and DSC methods) of these eleven-membered rings suggested the loss of a phenyl group in the first decomposition step. The decomposition temperature decreased from the Si containing heterocycle to Ge and was lowest for the Sn containing heterocycle.

Structural and Conformational Aspects in the Chemistry of Heterocycles

“…The activation energies and Gibbs activation energies decrease in the order atranes > ocanes > hypoatranes and Si > Ge. Even larger, 11-membered tetrel atoms (Si, Ge, Sn) containing heterocycles were synthesized and structurally investigated by a group of German chemists [ 3 ]. The Sn and Ge congeners were crystallized, but in quite different conformations which were attributed to different size and bond lengths with the tetrel atom.…”

A theoretical and empirical investigation into the growth of ultralong carbon nanotubes

“…And the nano coils were observed in the iron-tin (Fe-Sn) sample could be attributed to the fivemembered rings systems 60 . These results match those observed in earlier studies by Li 61 .…”