CH3-CH(OH)(CN)







 








 








 









Nitrogen


Nuclear Quadrupole Coupling Constants


in Lactonitrile


 








 








 








Diagonal components of the 14N nqcc tensors in each of two conformers of lactonitrile were first determined by Caminati et al. [1] in 1985 and revisited in 2006 by Apponi et al. [2].  Calculation was made here of the nqcc tensors on molecular structures given by MP2/6-311+G(3df,3pd) optimization with approximate re correction of the C-C and CN bond lengths.  These structures are shown below.  Calculated and experimental nqcc's [2] are compared in Tables 1 and 2.  Structure parameters are given in Table 3, rotational constants in Table 4.

 








Conformer I

Conformer II

























 








EI < EII by 0.20 kcal/mol as calculated at the B3PW91/6-311+G(df,pd) level of theory.

 








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.  z,CN (degrees) is the angle between the z-principal axis and the CN bond direction.  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 for the B3PW91/6-311+G(df,pd) model for calculation of the nqcc's, which may be taken as an estimate of the uncertainty in the calculated nqcc's.

 








  








   







Table 1.  Nitrogen nqcc's in CH3-CH(OH)CN, Conformer I (MHz).  

 









Calc.
Expt. [2]
   







14N Xaa - 4.089 - 4.08723(137)


Xbb
2.315
2.29960 **


Xcc
1.774
1.78764 **


|Xab|
0.035 *




|Xac|
1.280




|Xbc|
0.211



 







RMS
0.012 (0.43 %)




RSD
0.030 (1.3 %)



 







Xxx
1.936




Xyy
2.421




Xzz - 4.357




ETA
0.111




z,CN
0.22



 






   








* The algebraic sign of the product XabXacXbc is negative.

** Derived here from Xaa and Xbb - Xcc  = 0.51196(280) MHz.

 








 








   







Table 2.  Nitrogen nqcc's in CH3-CH(OH)CN, Conformer II (MHz).  

 









Calc.
Expt. [2]
   







14N Xaa - 4.055 - 4.053(45)


Xbb
2.184
2.1765 **


Xcc
1.870
1.8765 **


|Xab|
0.034 *




|Xac|
1.370




|Xbc|
0.268



 







RMS
0.006 (0.22 %)




RSD
0.030 (1.3 %)



 







Xxx
1.924




Xyy
2.433




Xzz - 4.357




ETA
0.117




z,CN
0.34



 







 








* The algebraic sign of the product XabXacXbc is negative.

** Derived here from Xaa and Xbb - Xcc  = 0.300(20) MHz.

 








 


Table 3.  Lactonitrile.  Selected structure parameters of conformers I and II ( and degrees).  Complete structures are given here in Z-matrix (G03 input) format.
 




    I     II





C=C 1.5145 1.5194

CO 1.4151 1.4132

OH 0.9615 0.9620

C-C 1.4756 1.4761

CN 1.1565 1.1564

C=CO
107.26 112.66

COH
108.92 108.26

C=C-C
110.74 110.13

C-CN
179.18 177.95


 








 













Table 4.  Lactonitrile.  Rotational constants (MHz).  
 



 
Conformer I  Calc.  Expt. [2]







A 8888.3 8790.20855(106)


B 4021.2 4005.854834(313)


C 2998.4 2975.800820(303)







Conformer II








A 8653.6 8584.059(135)


B 4047.3 4028.6686(306)


C 3009.8 2987.8407(64)


 








 








[1] W.Caminati, R.Meyer, M.Oldani, and F.Scappini, J.Chem.Phys.83,3729(1985).

[2] A.Apponi, J.J.Hoy, L.M.Ziurys, M.A.Brewster, A.F.Jalbout, and L.Adamowicz, 65th OSU International Symposium on Molecular Spectroscopy, 2006.  PDF

 








 








Table of Contents




Molecules/Nitrogen




 








 













CH3CHOHCN.html






Last Modified 13 May 2010