Vibrational spectra and structural features of carbene analogs ElII(OCH2CH2NMe2)2 and ClElIIOCH2CH2NMe2 (ElII = Ge, Sn, Pb) |
| |
Authors: | R R Aysin L A Leites S S Bukalov V N Khrustalev I V Borisova N N Zemlyanskii A Yu Smirnov and M S Nechaev |
| |
Institution: | (1) Faculty of Chemistry, Iran University of Science and Technology, PO Box 14155-4838, Tehran, Islamic Republic of Iran;(2) Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, PO Box 14155-4838, Tehran, Islamic Republic of Iran; |
| |
Abstract: | Vibrational spectra of compounds of divalent Group 14 elements ElII(OCH2CH2NMe2)2 with ElII = Ge (1), Sn (2), Pb (3) and ClElIIOCH2CH2NMe2 with ElII = Ge (4) and Sn (5) were measured for the first time and analyzed within the framework of DFT calclations. Monomeric compounds 1 and 2 whose molecules are stabilized only through intramolecular coordination were confirmed to be isostructural. Unlike 1 and 2, plumbylene 3 is a polymer in both solution and the crystalline state; the latter was confirmed by X-ray diffraction analysis. The νs
C-N stretching frequency in the CH2NMe2 fragment was shown to decrease by 80–100 cm−1 owing to the formation of the coordination bond El←N. To elucidate the mechanism of a dynamic flip-flop process suggested earlier based on the broadening of some signals in the NMR spectra of compounds 1 and 4, the Raman spectra of solutions of compounds 1 and 2 in THF and Py were obtained. These experiments revealed no equilibrium with participation of a stable form with one coordination
bond El←N cleaved along with the starting molecule. This is consistent with the results of the corresponding quantum chemical
calculations of thermo-dynamic parameters. A somewhat different, more probable mechanism of the dynamic process was proposed,
which involves an overturn of the CH2NMe2 fragment with cleavage of the El←N bond in the transition state only. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|