C6H11NO2














 









Nitrogen


Nuclear Quadrupole Coupling Constants


in Pipecolic Acid


 


















Calculations of the nitrogen nqcc tensors in Pipecolic Acid was made on B3LYP/cc-pVTZ optimized molecular structures (ropt) of the conformers shown below.  These are two of nine different conformers observed in the microwave spectrum by Simão et al. [1].   These calculated nqcc's are compared with the experimental results in Tables 1 and 2.  Structure parameters are given in Table 3,  rotational constants in Table 4.

 








                       Conformer I

     Conformer II                          





























                                     deltaCalpha-a-II

         alphaCdelta-a-II











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.  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 nitrogen  efg's/nqcc's.

 








 








   






Table 1.  Nitrogen nqcc's in Conformer I of Pipecolic Acid (MHz).  Calculation was made on ropt = B3LYP/cc-pVTZ molecular strcuture.
   









Calc
Rotamer I [1]
   






14N Xaa -
 1.177
 -
 1.2363(25)


Xbb -
 0.821
 -
 0.8201(34)


Xcc
1.998
2.0564(34)


Xab
3.631




Xac -
 1.006




Xbc
0.619












RMS
0.048 (3.5 %)




RSD
0.030 (1.3 %)












Xxx
2.087




Xyy
2.743




Xzz -
 4.830




ETA
0.136












 








 







 
   






Table 2.  Nitrogen nqcc's in Conformer II of Pipecolic Acid (MHz).  Calculation was made on ropt = B3LYP/cc-pVTZ molecular strcuture.
   









Calc
Rotamer II [1]
   






14N Xaa
0.584
0.555(15)


Xbb -
 1.628
 -
 1.668(10)


Xcc
1.044
1.112(10)


Xab
2.907




Xac -
 1.328




Xbc
2.168












RMS
0.049 (4.4 %)




RSD
0.030 (1.3 %)












Xxx
2.123




Xyy
2.622




Xzz -
 4.745




ETA
0.105












 








 












Table 3. Pipecolic Acid  B3LYP/cc-pVTZ optimized structure parameters.





 C
 C,1,B1
 C,2,B2,1,A1
 C,3,B3,2,A2,1,D1,0
 C,4,B4,3,A3,2,D2,0
 N,1,B5,2,A4,3,D3,0
 H,6,B6,1,A5,2,D4,0
 H,3,B7,2,A6,1,D5,0
 H,3,B8,2,A7,1,D6,0
 H,1,B9,6,A8,5,D7,0
 H,1,B10,6,A9,5,D8,0
 H,2,B11,1,A10,6,D9,0
 H,2,B12,1,A11,6,D10,0
 H,4,B13,3,A12,2,D11,0
 H,4,B14,3,A13,2,D12,0
 H,5,B15,4,A14,3,D13,0
 C,5,B16,4,A15,3,D14,0
 O,17,B17,5,A16,4,D15,0
 O,17,B18,5,A17,4,D16,0
 H,19,B19,17,A18,5,D17,0
 Conformer I








 B1=1.52907435
 B2=1.53054366
 B3=1.53035372
 B4=1.53388296
 B5=1.4743613
 B6=1.01144893
 B7=1.09383092
 B8=1.09106734
 B9=1.09028904
 B10=1.09398136
 B11=1.09521709
 B12=1.09221556
 B13=1.09392925
 B14=1.088914
 B15=1.0941119
 B16=1.54245612
 B17=1.20070458
 B18=1.34231263
 B19=0.98163813
 A1=110.20682392
 A2=110.72346801
 A3=112.08627185
 A4=114.11986342
 A5=110.12855644
 A6=109.49507532
 A7=110.66957492
 A8=107.53887181
  A9=107.73702102
 A10=109.58038351
 A11=109.48415969
 A12=109.27774531
 A13=110.93831662
 A14=108.60475588
 A15=112.708301
 A16=123.92938151
 A17=113.2878673
 A18=104.99572267
 D1=-55.79288218
 D2=52.36520198
 D3=54.26838484
 D4=76.03966423
 D5=65.06795447
 D6=-177.79553096
 D7=-172.64750187
 D8=72.6894973
 D9=-66.66723037
 D10=176.44748682
 D11=-67.61621366
 D12=174.06353943
 D13=-166.18580897
 D14=79.33416036
 D15=30.34065623
 D16=-152.4780923
 D17=4.90448485









 


 C
 C,1,B1
 C,2,B2,1,A1
 C,3,B3,2,A2,1,D1,0
 C,4,B4,3,A3,2,D2,0
 N,1,B5,2,A4,3,D3,0
 H,6,B6,1,A5,2,D4,0
 H,3,B7,2,A6,1,D5,0
 H,3,B8,2,A7,1,D6,0
 H,1,B9,6,A8,5,D7,0
 H,2,B10,1,A9,6,D8,0
 H,2,B11,1,A10,6,D9,0
 H,4,B12,3,A11,2,D10,0
 H,4,B13,3,A12,2,D11,0
 H,5,B14,4,A13,3,D12,0
 H,5,B15,4,A14,3,D13,0
 C,1,B16,6,A15,5,D14,0
 O,17,B17,1,A16,6,D15,0
 O,17,B18,1,A17,6,D16,0
 H,19,B19,17,A18,1,D17,0
 Conformer II








 B1=1.52776285
 B2=1.53402792
 B3=1.53387932
 B4=1.53265468
 B5=1.47281021
 B6=1.01725105
 B7=1.09496543
 B8=1.09108548
 B9=1.09773969
 B10=1.0944323
 B11=1.08923184
 B12=1.09506678
 B13=1.09238382
 B14=1.0905573
 B15=1.09333997
 B16=1.53088401
 B17=1.19973859
 B18=1.34587697
 B19=0.97829018
 A1=109.67849865
 A2=111.7462605
 A3=111.45708573
 A4=113.41185216
 A5=108.29171962
 A6=108.96451886
 A7=110.19288969
 A8=105.92365581
  A9=108.98584751
 A10=109.87536616
 A11=109.4829706
 A12=110.54779143
 A13=111.02318397
 A14=110.13419284
 A15=109.84858596
 A16=124.00935465
 A17=113.5163225
 A18=106.11968441
 D1=-51.99241915
 D2=51.30405668
 D3=55.43371027
 D4=61.37280582
 D5=68.71665808
 D6=-174.90576205
 D7=61.18299748
 D8=-65.43390988
 D9=178.07347626
 D10=-69.11681769
 D11=173.75066152
 D12=-174.39052844
 D13=67.30492034
 D14=173.79021747
 D15=156.78109878
 D16=-25.29285906
 D17=3.85905368







 













Table 4:  Pipecolic Acid, Rotational Constants (MHz).

 





   ropt Rotamers I and II [1]






Conformer I
 A   2582.
 2546.08754(57)


B   1404.
 1437.99330(58)


C   1117.
 1148.37819(72)






Conformer II
 A
   3206. 3199.4725(16)


B
   1150. 1155.5398(10)


C
     889.   893.34360(65)


 








 








[1] A.Simão, C.Cabezas,  I.León, E.R.Alonso, S.Mata, and J.L.Alonso, PCCP, 21,4155(2019).

 








 








Table of Contents




Molecules/Nitrogen




 








 













Pipecolic_acid.html






Last Modified 11 March 2019