(CF3)2C=NH


















 




 








Nitrogen

Nuclear Quadrupole Coupling Constants

in transoidal Hexafluoroacetone imine

 








 








 








Nitrogen nqcc's in hexafluoroacetone imine were determined by Grubbs II et al. [1].  

 








Calculation of the 14N nqcc tensors was made here on molecular structures derived by MP2/6-311+G(d,p), MP2/6-311+G(df,pd), and MP2/6-311+G(3df,3pd) optimizations.  Calculated and experimental nqcc's are compared in Table 1.  Structure parameters are given in Table 2, rotational constants and dipole moment components in Table 3.

 








In Table 1, subscripts a,b,c refer to the principal axes of the inertia tensor; x,y,z to the principal axes of the nqcc tensor.  Øz,bi (degrees) is the angle between the z-principal axis and the bisector or the C=NH angle.  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.

 








 








   









Table 1.  14N nqcc's in (CF3)2C=NH (MHz).  Calculation was made on (1) MP2/6-311+G(d,p), (2) MP2/6-311+G(df,pd), and (3) MP2/6-311+G(3df,3pd) optimized molecular structures.
   











Calc. (1)
Calc. (2)
Calc. (3)
Expt. [1]
   









Xaa - 3.101 - 3.044 - 3.083 - 3.050(17)

Xbb - 0.980 - 1.015 - 1.026 - 1.008(22)

Xcc
4.081
4.059
4.109
4.058(14)

Xab
2.420
2.431
2.461



Xac - 0.242 - 0.238 - 0.228



Xbc
0.075
0.074
0.069



 









RMS
0.036 (1.3 %) 0.005 (0.20 %) 0.036 (1.3 %)


RSD
0.030 (1.3 %) 0.030 (1.3 %) 0.030 (1.3 %)


 









Xxx
0.600
0.604
0.612



Xyy
4.090
4.066
4.116



Xzz - 4.690 - 4.670 - 4.728



ETA
0.744
0.741
0.741



Øz,bi *
1.12
1.57
1.52



 










 








* Angle between the z-principal axis and the bisector or the C=NH angle.

 








 














Table 2.  (CF3)2C=NH.  Selected structure parameters (Å and degrees).  Complete structures are given here in Z-matrix format.
 





  ropt (1) = MP2/6-311+G(d,p) optimization.


ropt (2) = MP2/6-311+G(df,pd) optimization.


ropt (3) = MP2/6-311+G(3df,3pd optimization.
 






ropt (1) ropt (2) ropt (3)






C(2)C(4) 1.5254 1.5267 1.5237
C(2)C(3) 1.5275 1.5289 1.5256
C(2)N 1.2712 1.2672 1.2646
NH 1.0242 1.0229 1.0207
C(4)C(2)C(3) 116.36 116.32 116.18
C(4)C(2)N 118.60 118.68 118.99
C(3)C(2)N 125.02 124.99 124.82
C(2)NH 110.05 110.01 110.50
 






 








 




Table 3.  (CF3)2C=NH.  Rotational constants (MHz) and dipole moment components (D). 
 





ropt (1) = MP2/6-311+G(d,p) optimization.

ropt (2) = MP2/6-311+G(df,pd) optimization.

ropt (3) = MP2/6-311+G(3df,3pd) optimization.







  Calc. ropt (1) Calc. ropt (2) Calc. ropt (3)    Expt. [1]







A 2159.1 2183.1 2175.4 2143.0309(12)

B 1045.4 1052.3 1052.6 1044.50289(24)

C   938.0   943.7   944.2   934.5118(11)

 




|µa|  1.45  1.46  1.44

|µb|  0.92  0.84  0.89

|µc|  0.01  0.01  0.01


 








 








Note:  The Cs conformer of this molecule, with one imaginary frequency (as calculated at the MP2/6-311+G(d,p) level of theory), is a first order transition state connecting two lower energy conformers, presumely this transoidal conformer and its mirror image conformer.  E(Cs) > E(transoid) by about 2.6 kJ/mole.

 








 








[1] G.S.Grubbs II, C.T.Dewberry, B.E.Long, W.C.Pringle, and S.A.Cooke, 66th International Symposium on Molecular Spectroscopy, Ohio State University, 2011, Abstract WH14.

 








D.A.Obenchain, D.J.Frohman, G.S.Grubbs II, B.E.Long, W.C.Pringle, S.E.Novick, and S.A.Cooke, 67th International Symposium on Molecular Spectroscopy, Ohio State University, 2012, Abstract TC04.

 








 








H2C=NH F2C=NH F2C=NF trans-syn-Propenimine

t-Ethanimine c-Ethanimine H2C=NOH trans-anti-Propenimine

 








 








Table of Contents




Molecules/Nitrogen




 








 













CF32CNH.html






Last Modified 7 July 2011