H2NCHO			PDF
	Nitrogen
	Nuclear Quadrupole Coupling Constants
		in Formamide
	Nitrogen nqcc's in formamide were determined in 1971 by Kukolich and Nelson [1]; 1973 by Kirchoff and Johnson [2]; and 2009 by Kryvda et al. [3]; and in 2013 in several deuterated species by Kutsenko et al. [4].  A substitution structrure was derived by Hirota et al. [5], an equilibrium structure by Demaison et al. [6].
	Calculation of the nqcc's was made here on the equilibrium and substitution structures, and on ab initio structures given by HF/6-311++G(3df,3pd) and HF/aug-cc-pVTZ optimizations.  Calculated nqcc's are compared with the experimental nqcc's [3] in Tables 1 - 3.  Structure parameters are given in Table 4, 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 nitrogen nqcc's, which may be taken as an estimate of the uncertainty in the calculated nqcc's.
	Table 1.  14N nqcc's in NH2CHO (MHz).  Calculation was made on the (1) equilibrium and (2) substitution structures.     Calc. (1) Calc. (2) Expt. [3]     Xaa 1.997 1.972 1.9543(12) Xbb 1.924 1.915 1.89665 * Xcc - 3.921 - 3.888 - 3.85095 * |Xab| 0.033 0.062   RMS 0.050 (1.9 %) 0.026 (1.0 %) RSD 0.030 (1.3 %) 0.030 (1.3 %)   Xxx 1.911 1.875 Xyy 2.010 2.012 Xzz - 3.921 - 3.888 ETA 0.025 0.035 Øx,a 68.70 57.27 Øa,NC 24.88 25.13 Øx,NC 43.82 32.15
	* Calculated here from experimental Xaa and Xbb - Xcc = 5.7476(18) MHz.
	Table 2.   14N nqcc's in NH2CHO (MHz).  Calculation was made on the (1) HF/6-311++G(3df,3pd) and (2) HF/aug-cc-pVTZ optimized structures.     Calc. (1) Calc. (2) Expt. [3]     Xaa 1.962 1.963 1.9543(12) Xbb 1.918 1.915 1.89665 * Xcc - 3.880 - 3.878 - 3.85095 * |Xab| 0.025 0.022   RMS 0.021 (0.83 %) 0.020 (0.76 %) RSD 0.030 (1.3 %) 0.030 (1.3 %)   Xxx 1.907 1.906 Xyy 1.973 1.972 Xzz - 3.880 - 3.878 ETA 0.017 0.017 Øx,a 65.84 68.63 Øa,NC 24.45 24.48 Øx,NC 41.38 44.15
	* Calculated here from experimental Xaa and Xbb - Xcc = 5.7476(18) MHz.
	Table 3.  14N nqcc's in deuterated NH2CHO (MHz).  Calculation was made on the (1) equilibrium and (2) substitution structures.     Calc. (1) Calc. (2) Expt. [4]   NH2CDO Xaa 1.997 1.972 1.889(23) Xbb - Xcc 5.845 5.803 5.896(19) |Xab| 0.034 0.062   c-NHDCHO Xaa 1.994 1.968 1.973(48) Xbb - Xcc 5.848 5.808 5.864(21) |Xab| 0.036 0.064   t-NHDCHO Xaa 1.998 1.975 2.025(61) Xbb - Xcc 5.844 5.800 5.861(27) |Xab| 0.032 0.061   ND2CHO Xaa 1.996 1.970 1.941(60) Xbb - Xcc 5.846 5.805 5.869(36) |Xab| 0.034 0.063
	Table 4. Molecular structure parameters (Å and degrees).     ropt (1)  HF/6-311++G(3df,3pd) ropt (2)  HF/aug-cc-pVTZ   reBO [6] rs [5] ropt (1) ropt (2) NHc 1.0033 1.0016 0.9920 0.9918 NHt 1.0006 1.0015 0.9890 0.9888 C-N 1.3547 1.352 1.3457 1.3461 C=O 1.2097 1.219 1.1861 1.1878 CH 1.1001 1.098 1.0914 1.0912 HcNC 119.18 118.5 119.49 119.51 HtNC 121.09 120.0 121.23 121.21 NCO 124.63 124.7 124.87 124.87 NCH 112.53 112.7 112.90 112.92
	Table 5.  Rotational Constants (MHz).  Normal Species.   ropt (1) = HF/6-311++G(3df,3pd) optimization. ropt (2) = HF/aug-cc-pVTZ(G03) optimization.     Calc. ropt (1) Calc. ropt (2)    Expt. [3] A   75863.3   75793.1 72716.89738(20) B   11699.6   11682.0 11373.582427(32) C   10136.4   10121.9   9833.881122(30)
	[1] S.G.Kukolich and A.C.Nelson, Chem.Phys.Lett. 11,383(1971).
	[2] W.H.Kirchoff and D.R.Johnson, J.Mol.Spectrosc. 45,159(1973).
	[3] A.V.Kryvda, V.G.Gerasimov, S.F.Dyubko, E.A.Alekseev, R.A.Motiyenko, J.Mol.Spectrosc. 254,28(2009).
	[4] A.S.Kutsenko, R.A.Motiyenko. L.Margulès, A&A 549,A128(2013).
	[5] E.Hirota, R.Sugisaki, C.J.Nielsen, and G.O.Sørensen, J.Mol. Spectrosc. 49,251(1974).
	[6] J.Demaison, A.G.Császár, I.Kleiner, and H.Møllendal, J.Chem.Phys.A 111,2574(2007).
	H2NCHS		NH2OH		NH2Cl		NH2F
	BH2NH2		BF2NH2		PF2NH2		B2H5NH2
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						Last Modified 6 Sept 2013