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.  (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



z,a
14.61
14.70



a,N=C







z,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




z,a
13.30

14.31




a,N=C







z,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) ( and degrees).  Complete structures are given here in Z-matrix format.
 



  trans
    ro    rsB3LYP
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


 


















Table of Contents




Molecules/Nitrogen




 








 













CH3CH2NCO.html






Last Modified 24 Feb 2014