CH3CH2N=C=O
		Nitrogen
	Nuclear Quadrupole Coupling Constants
		in Ethylisocyanate
	Calculation was made of the 14N nqcc tensor in trans and cis ethylisocyanate.  For the trans conformer, calculation was made on the experimental ro and rs structures of Heineking et al. [1]; and on ropt structures given by B3LYP/6-311+G(3df,3pd) and MP2/6-311+G(3df,3pd) optimization.  For the cis conformer, calculation was made on these B3LYP and MP2 ropt structures.
	trans-ethylisocyanate					cis-ethylisocyanate
	At the MP2/6-311+G(3df,3pd) level of theory, Ecis < Etrans by 1.0 kJ/mol.
	In Tables 1 and 2, calculated nqcc's in the trans conformer are compared with the experimental values of Heineking et al. [1].  In Table 3, nqcc's in the cis conformer are compared with the experimental values of Kasten et al. [2].  In Tables 1-3,  subscripts a,b,c refer to the principal axes of the inertia tensor.   Subscripts x,y,z refer 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 (percent of average experimental nqcc).  RSD is the residual standard deviation of calibration of the B3PW91/6-311+G(df,pd) model for calculation of the efg's/nqcc's.  Structure parameters are given in Table 4.
	Table 1.  14N nqcc's in trans-CH3CH2N=C=O (MHz).  Calculation was made on the ro and rs structures of Heineking et al. [1].     Calc. ro Calc. rs Expt. [1]     Xaa 2.456 2.416 2.5488(6) Xbb - Xcc 0.396 0.376 0.2054(15) Xbb - 1.030 - 1.020 - 1.1717 Xcc - 1.426 - 1.396 - 1.3771(8) |Xab| 0.974 0.968   RMS 0.102 (6.0 %) 0.117 (6.9 %) RSD 0.030 (1.3 %) 0.030 (1.3 %)   Xxx - 1.426 - 1.396 - 1.377 Xyy - 1.284 - 1.274 - 1.424 Xzz 2.710 2.670 2.801 ETA - 0.0525 - 0.0457 Øz,a 14.61 14.70 Øa,N=C Øz,N=C
	Table 2.  14N nqcc's in trans-CH3CH2N=C=O (MHz).  Calculation was made on B3LYP/6-311+G(3df,3pd) and MP2/6-311+G(3df,3pd) roptstructures.     Calc. B3LYP Calc. MP2 Expt. [1]     Xaa 2.561 2.579 2.5488(6) Xbb - Xcc 0.532 0.594 0.2054(15) Xbb - 1.014 - 0.992 - 1.1717 Xcc - 1.546 - 1.589 - 1.3771(8) |Xab| 0.922 0.834   RMS 0.134 (7.9 %) 0.160 (9.4 %) RSD 0.030 (1.3 %) 0.030 (1.3 %)
	Table 3.  14N nqcc's in cis-CH3CH2N=C=O (MHz).  Calculation was made on B3LYP/6-311+G(3df,3pd) and MP2/6-311+G(3df,3pd) roptstructures.     Calc. B3LYP Calc. MP2 Expt. [2]     Xaa 2.604 2.567 Xbb - 1.164 - 1.112 Xcc - 1.439 - 1.455 - 1.39(2) |Xab| 0.944 1.004   RMS RSD 0.030 (1.3 %) 0.030 (1.3 %)   Xxx - 1.439 - 1.455 Xyy - 1.388 - 1.368 Xzz 2.827 2.823 ETA - 0.0182 - 0.0306 Øz,a 13.30 14.31 Øa,N=C Øz,N=C
	Table 4.  CH3CH2N=C=O.  Heavy atom structure parameters, ro and rs [1], B3LYP/6-311+G(3df,3pd) and MP2/6-311+G(3df,3pd) (Å and degrees).  Complete structures are given here in Z-matrix format.     trans     ro    rs B3LYP MP2 C(1)C(2) 1.523(8) 1.531(11) 1.5211 1.5157 C(2)N 1.441(6) 1.439(8) 1.4487 1.4472 NC(4) 1.189(13) 1.188(19) 1.1968 1.2084 C(4)O 1.184(12) 1.194(19) 1.1717 1.1782 C(1)C(2)N 113.7(4) 113.5(5) 110.97 109.86 C(2)NC(4) 138.2(8) 138.8(12) 139.98 137.66 NC(4)O 175.7(17) 175.6(26) 173.97 172.96    cis B3LYP MP2 C(1)C(2) 1.5234 1.5182 C(2)N 1.4450 1.4439 NC(4) 1.1959 1.2075 C(4)O 1.1726 1.1790 C(1)C(2)N 113.76 112.64 C(2)NC(4) 140.77 137.62 NC(4)O 173.94 173.06
	[1] N.Heineking, J.-U.Grabow, and W.Stahl, Mol.Phys. 81,1177(1994).
	[2] W.Kasten, H.Dreizler, and U.Andresen, J.Mol.Struct. 97,221(1983).
	T.Sakaizumi, O.Yamada, K.Ushida,  O.Ohashi, and I.Yamaguchi, Bull.Chem.Soc. Jpn.49(11), 2908(1976).
	HNCO		CH3NCO		(CH3)3CNCO		CH2=C(H)NCO
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	Molecules/Nitrogen
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						Last Modified 24 Feb 2014