C2H4NH					PDF
	Nitrogen
	Nuclear Quadrupole Coupling Constants
		in Ethyleneimine
			(Aziridine)
	Nitrogen nqcc's in ethyleneimine were first determined in 1968 by Kemp and Flygare [1] and later, with improved resolution, by Thorwirth et al. [2,3].  An rs structure was determined by Bak and Skaarup [4], an reSE structure by Császár et al. [5].
	Calculation was made here of the nqcc's on the rs and reSE structures, and on an ropt structure given by B3LYP/6-31G(3d,3p) optimization.  These are compared with the experimental nqcc's in the normal species [2] in Table 1, and with the ND species [1] in Table 2.  Structure parameters are given in Table 3, atomic coordinates in Table 4, and rotational constants in Table 5.
	In Tables 1 and 2, subscripts a,b,c refer to the principal axes of the inertia tensor; x,y,z to the principal axes of the nqcc tensor.  Ø (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.  RMS is the root mean square difference between calculated and experimental diagonal nqcc's (percentage of the average of the magnitudes of the experimental nqcc's).  RSD is the calibration residual standard deviation of the B3PW91/6-311+G(df,pd) model for calculation of the nitrogen efg's/nqcc's.
	Table 1. 14N nqcc's in Ethyleneimine-NH (MHz).  Calculation was made on the rs, reSE, and ropt molecular structures.   Calc /rs Calc /reSE Calc /ropt Expt. [2]   Xaa 0.671 0.687 0.692 0.68483 Xbb 2.171 2.164 2.178 2.17235(95) Xcc - 2.842 - 2.851 - 2.870 - 2.85718(88) |Xbc| 2.262 2.271 2.273 RMS 0.012 (0.61 %) 0.006 (0.34 %) 0.009 (0.47 %) RSD 0.030 (1.3 %) 0.030 (1.3 %) 0.030 (1.3 %) Xxx 0.671 0.687 0.692 0.68483 Xyy 3.041 3.039 3.050 3.047 * Xzz - 3.712 - 3.727 - 3.742 - 3.732 ETA 0.638 0.631 0.630 0.633 Øz,c 21.03 21.09 21.00 21.05 Øc,NH 26.69 26.79 27.24 27.24 Øz,NH 47.72 47.88 48.24 48.29 Øz,bi **   8.52   8.40   8.28   8.31
	* Calculated here from the diagonal experimental diagonal nqcc's and |Xbc| = 2.273 MHz.
	** Angle between the z-axis and the bisector ('bi') of the angle the NH bond axis makes with the CNC plane.
	Table 2. 14N nqcc's in Ethyleneimine-ND (MHz).  Calculation was made on the rs, reSE, and ropt molecular structures.   Calc /rs Calc /reSE Calc /ropt Expt. [1]   Xaa 2.465 2.459 2.473 2.450(5) Xbb 0.671 0.687 0.692 0.685(5) Xcc - 3.136 - 3.146 - 3.165 - 3.135(5) |Xac| 2.262 1.895 1.894 1.844(80) RMS 0.012 (0.56 %) 0.008 (0.38 %) 0.018 (0.84 %) RSD 0.030 (1.3 %) 0.030 (1.3 %) 0.030 (1.3 %)
	Table 3.  Ethyleneimine.  Molecular structure parameters, rs, reSE, and ropt (Å and degrees).  These structures are given here in Z-matrix format.  Hc and Ht are cis and trans with respect to NH.      rs   reSE   ropt NH 1.016 1.01279(13) 1.0169 NC 1.475 1.47013(6) 1.4730 CC 1.481 1.47703(8) 1.4807 CHc 1.084 1.08099(13) 1.0863 CHt 1.083 1.07971(13) 1.0853 CNC   60.25   60.311(6)   60.35 CNH 109.31 109.376(9) 109.79 NCHc 118.26 118.28(2) 118.69 CCHc 117.75 117.829(14) 118.08 NCHt 114.27 114.46(2) 114.69 CCHt 119.32 119.538(14) 119.97 HcCHt 115.72 115.424(9) 114.63
	Table 4.  Ethyleneimine-NH.  Atomic coordinates, ropt structure. (More figures are shown than are significant.)   a (Å)   b (Å)   c (Å) N 0.0 0.840294 - 0.083125 H 0.0 1.305816 0.820991 C ± 0.740365 - 0.429721 0.009899 H ± 1.251640 - 0.668577 0.938088 H ± 1.282555 - 0.705381 - 0.888965
	Table 5.  Ethyleneimine-NH.  Rotational Constants (MHz).      ropt      Expt. [2] A    22 881 22 736.192 853(299) B    21 258 21 192.461 027(303) C    13 452 13 383.163 814(289)
	[1] M.K.Kemp and W.H.Flygare, J.Am.Chem.Soc. 90,6267(1968).
	[2] S.Thornwirth, R.Gendriesch, H.S.P.Müller, F.Lewen, and G.Winnewisser, J.Mol.Spectrosc. 201,323(2000).
	[3] S.Thorwirth, H.S.P.Müller, and G.Winnewisser, J.Mol.Spectrosc. 199,116(2000).
	[4] B.Bak and S.Skaarup, J.Mol.Struct. 10,385(1971).
	[5] A.G.Császár, J.Demaison, and H.D.Rudolph, J.Phys.Chem. A, 119(9),1731(2015).
	CH2NH		(CH3)2NH		CF2NH
	trans-syn-Propenimine			trans-anti-Propenimine
	trans-Ethanimine			cis-Ethanimine
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	Molecules/Nitrogen
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