HOCH2CN


























Nitrogen


Nuclear Quadrupole Coupling Constants


in Hydroxyacetonitrile



 








 








 








Calculation of the nitrogen nqcc tensors in the gauche and trans conformers of hydroxyacetonitrile was made on molecular structures given by MP2/aug-cc-pVTZ optimization with approximate re CC and CN bond lengths.  These calculated nqcc's are compared with the experimental values for the gauche conformer [1] in Table 1, and are given for the trans conformer in Table 2.  Structure parameters are given in Table 3 in Z-matrix format, rotational constants and dipole moments in Table 4, quartic centrifugal distortions constants in Table 5.


 








trans Cs

gauche C1

cis Cs
























Local Minimum

Global Minimum

TS Saddle Point


 









At the B3LYP/cc-pVTZ and MP2/cc-pVTZ levels of theory respectively, trans hydroxyacetonitrile is higher in energy than gauche by 7.7/7.1 kJ/mol, while cis is higher than gauche by 5.3/5.9 kJ/mol.  The cis conformer - with one imaginary frequency - is a saddle point on the PE surface, presumable connecting equivalent mirror image gauche conformers.












In Tables 1 and 2, RMS is the root mean square difference between calculated and experimental diagonal nqcc's.  RSD is the calibration residual standard deviation of the B3PW91/6-311+G(df,pd) model for calculation of the nitrogen nqcc's.

Subscripts a,b,c refer to the principal axes of the inertia tensor; x,y,z to the principal axes of the nqcc tensor.  ETA = (Xxx - Xyy)/Xzz.  Ø (degrees) is the angle between its subscripted parameters.


 








 








   







Table 1. Nitrogen nqcc's in gauche HOCH2CN (MHz).  Calculation was made on a molecular structure given by MP2/aug-cc-pVTZ optimization with approximate re CC and CN bond lengths.
   










Calc.
Expt [1]

   







14N Xaa - 3.561 -
3.63



Xbb
1.697
1.64



Xcc
1.864

1.99



Xab
2.248





Xac
0.011





Xbc -
0.055




 







RMS

0.097 (4.0 %)





RSD
0.030 (1.3 %)



 







Xxx
2.531




Xyy
1.861




Xzz - 4.392




ETA
0.152




Øz,CN
0.31




 







 








 









   







Table 2. Nitrogen nqcc's in trans HOCH2CN (MHz).  Calculation was made on a molecular structure given by MP2/aug-cc-pVTZ optimization with approximate re CC and CN bond lengths.
   










Calc.
Expt

   







14N Xaa - 3.564




Xbb
1.826




Xcc
1.828





Xab
2.122




 







RSD
0.030 (1.3 %)



 







Xxx
2.552




Xyy
1.828




Xzz - 4.380




ETA -
0.165




Øz,a
18.88





Øa,CN
18.54





Øz,CN
  0.34




 







 









 

Table 3.  Hydroxyacetonitrile.  MP2/aug-cc-pVTZ optimized molecular structure parameters (Å and degrees).  Approximate re bond lengths for CC and CN are given in parentheses.
 


 N
 C,1,B1
 C,2,B2,1,A1
 O,3,B3,2,A2,1,D1,0
 H,4,B4,3,A3,2,D2,0
 H,3,B5,2,A4,1,D3,0
 H,3,B6,2,A5,1,D4,0




trans

gauche



 B1=1.16963183   (1.1552)
 B2=1.46354819   (1.4640)
 B3=1.41816573
 B4=0.96343489
 B5=1.09243859
 B6=1.09243859
 A1=178.13717936
 A2=107.94457755
 A3=107.62920186
 A4=108.15046671
 A5=108.15046671
 D1=180.
 D2=180.
 D3=-58.75396373
 D4=58.75396373

 B1=1.17062545   (1.1559)
 B2=1.47132978   (1.4715)
 B3=1.41360373
 B4=0.96360414
 B5=1.09189219
 B6=1.0873618
 A1=178.20693054
 A2=112.48707348
 A3=108.43138072
 A4=108.41569433
 A5=108.85726323
 D1=-52.38789233
 D2=60.63215579
 D3=72.35692477
 D4=-170.15610614


 








 














Table 4.  Hydroxyacetonitrile.  Rotational Constants (MHz) and Dipole Moments * (D).








trans

gauche



Calc
Expt
Calc
  Expt [1]







A
35375

33515
33605.57(22)

B
  4873

  4853
  4840.44(4)

C
  4401

  4396
  4377.60(3)







a|
  4.10

  2.36


b|   2.90

  1.34


c|   0 (symmetry)

  1.34


* B3PW91/6-311+G(df,pd) dipole moments calculated on molecular structures given by MP2/aug-cc-pVTZ optimization with approximate re CC and CN bond lengths



 








 

















Table 5.  Hydroxyacetonitrile.  B3LYP/cc-pVTZ and MP2/cc-pVTZ Calculated Quartic Centrifugal Distortion Constants (kHz).











trans



gauche




B3LYP

MP2

B3LYP

MP2









Delta_J

2.57

2.64

3.06

3.08
Delta_JK -
58.5
-
59.7
-
63.9
-
65.0
Delta_K
1048.

1035.

950.

956.
delta_J
0.529

0.554

0.652

0.664
delta_K
15.6

16.1

17.7

18.0









D_J

2.51

2.58

3.00

3.01
D_JK-
58.2
-
59.4
-
63.5
-
64.6
D_K
1048.

1035.

950.

956.
d_1
-
0.528
-
0.554
-
0.652
-
0.664
d_2
-
0.0284
-
0.0303
-
0.0340
-
0.0348






















[1] G.Cazzoli, D.G.Lister, and A.M.Mirri, J.Chem.Soc. Faraday Trans. II 69,569(1973).


 









L.Margulès, R.A.Motiyenko, and J.C.Guillemin, Abstract TI13, 68th OSU International Symposium on Molecular Spectroscopy, 2013.


 









 









CH3CN FCH2CN ClCH2CN


 








 








Table of Contents




Molecules/Nitrogen




 








 













HOCH2CN.html






Posted 12 April 2013






Last Modified 22 Dec 2013