Structural and Conformational-Analysis of N-Chloro-N-Ethylethanamine by Gas Electron-Diffraction, Abinitio Calculations and Vibrational Spectroscopy.
by Kuze, N.; Takeuchi, H.; Egawa, T.; Konaka, S.; Newton, S. Q.; Schafer, L.
The structural and conformational properties of N-chloro-N-ethylethanamine, C(3)H3C(2)H2N(1)ClC(4)H2C(5)H3, were studied by gas electron diffraction (GED). Vibrational amplitudes and shrinkage corrections were calculated on the basis of a normal coordinate analysis of the vibrational spectra measured in the vapor and liquid phases. The geometries of six possible conformers were optimized by ab initio HF/4-21G*/3-3-21G* calculations and the results were used in the data analysis as structural constraints. At 25-degrees-C, two conformers were observed. On the basis of the GED data analysis it is possible to identify the trans-trans conformer (TT, dihedral angles phi1(C4N1C2C3) = -phi2(C2N1C4C5) = 175(1)-degrees) as the most stable one, but the nature of the minor component is uncertain, since various mixtures of TT with one of three different gauche forms, TG, TG' or GG', fit the experimental data reasonably well. The best fitting model is a mixture of TT and TG (dihedral angles phi1 = 80(6)-degrees and phi2 = - 175(1)-degrees), with a relative abundance of 68(8) and 32%, respectively. The vibrational spectra are consistent with the existence of two conformers in the vapor and liquid phases. The structural parameters of TT determined by this analysis (with error limits of 3sigma and average values in brackets) are r(g)(N-C) = 1.471(2) angstrom, r(g)(N-Cl) = 1.765(2) angstrom, r(g)(C-C) = 1.530(3) angstrom, [r(g)(C-H)] = 1.118(3) angstrom, angle (alpha)NCC = 112.6(4)-degrees, [angle (alpha)NCH] = 109.6(18)-degrees, angle (alpha)CNC = 110.6(8)-degrees, angle (alpha)CNCl = 108.3(2)-degrees, [angle (alpha)CCH] = 109.4(11)-degrees and phi1 = (-phi2) = 175(1)-degrees. The structural differences between the TT and TG conformers were taken from the calculated ones.
- Journal
- Journal of Molecular Structure
- Volume
- 291
- Issue
- 1
- Year
- 1993
- Start Page
- 11-22
- URL
- https://dx.doi.org/10.1016/0022-2860(93)80252-q
- ISBN/ISSN
- 1872-8014; 0022-2860
- DOI
- 10.1016/0022-2860(93)80252-q