CH2CN-C(=O)OH




































 









Nitrogen


Nuclear Quadrupole Coupling Constants


in Cyanoacetic Acid


 








 








Calculation of the 14N nqcc's was made here on aa approximate equilibrium molecular structure given by MP2/aug-cc-pVTZ optimization with corrected CN, C-C, and C=O bond lengths (~ re, see here).  These nqcc's are compared with the experimental values [1] in Table 1.  Structure parameters are given in Table 2, rotational constants 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.  The nqcc y-axis is chosen coincident with the inertia c-axis, these are perpendicular to the molecular symmetry plane.  ě (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 (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 efg's/nqcc's, which may be taken as an estimate of the uncertainty in the calculated nqcc's.

 








  








   







Table 1.  14N nqcc's in CH2CN-C(=O)OH (MHz).  Calculation was made on the ~ r structure.

 









Calc

Expt. [1]
   







14N Xaa -
3.224





Xbb
1.148





Xcc
2.076





|Xab|
2.483




 







RMS







RSD

0.030 (1.3 %)



 







Xxx
2.270





Xyy
2.076




Xzz -
4.346





ETA

0.0448





ěz,a






ěa,CN






ěz,CN





 






   








 












Table 2.  Cyanoacetic Acid.  MP2/aug-cc-pVTZ optimized molecular structure parameters, approximate equilibrium bond lengths are given in parentheses (┼ and degrees).
 


Point Group Cs







 O
 C,1,R1
 C,2,R2,1,A1
 C,3,R3,2,A2,1,D1,0
 H,3,R4,2,A3,1,D2,0
 H,3,R5,2,A4,1,D3,0
 O,2,R6,3,A5,4,D4,0
 H,7,R7,2,A6,1,D5,0
 N,4,R8,3,A7,2,D6,0
 









 R1=1.20389544         (1.1966)
 R2=1.51491664         (1.5131)
 R3=1.45459744         (1.4555)
 R4=1.09035638
 R5=1.09035638
 R6=1.35185006
 R7=0.97042033
 R8=1.16968559         (1.1553)
 A1=126.40264037
 A2=112.47289091
 A3=108.50342719
 A4=108.50342719
 A5=109.13798809
 A6=106.32402221
 A7=178.43430321
 D1=0.
 D2=122.10543854
 D3=-122.10543854
 D4=180.
 D5=0.
 D6=180.







 








 













Table 3.  Cyanoacetic Acid.  Rotational constants (MHz).

 



 
   ~ re    Expt [1]







A    10214.



B      2282.



C      1887.




 








 








[1] E.Johnson, S.Shipman, I.Leˇn, L.Kolesnikovß, S.Mata, J.L.Alonso, Abstract RK02, 73rd ISMS, Champaign-Urbana, Illinois, 2018.


 








 








CH2Cl-C(=O)OH
CH2Br-C(=O)OH


 








 








Table of Contents




Molecules/Nitrogen




 








 













CH2CNCOOH.html






Last Modified 3 May 2018