Piperidine

PDF  equatorial

C5H10NH

PDF  axial

 








 








 









Nitrogen and Deuterium


Nuclear Quadrupole Coupling Constants

in Piperidine (chair, eq and ax)

 








 








 

 





Calculation of the nitrogen nqcc's in equatorial and axial piperidine (chair) was made here on ropt molecular structures given by MP2/6-311+G(2d,2p) optimization.  For the equatorial conformer, a semi-experimental equilibrium structure, reSE, was derived by Demaison et al [1].  Calculation was made also on this structure.  These are compared with the experimental nqcc's [2] in Tables 1 - 4.  Structure parameters are given in Table 5, rotational constants in Table 6.

 








In Tables 1 - 4, 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 b-axis, these are perpendicular to the molecular symmetry plane.  Ø (degrees) is the angle between its subscripted parameters.  ETA = (Xxx - Xyy)/Xzz.

 








RMS is the root mean square difference between calculated and experimental nqcc's (percentage of the average of the magnitudes of the experimental nqcc's).  RSD is the calibration residual standard deviation of the models for calculation of nitrogen and deuterium efg's/nqcc's.

 








 








 
 







Table 1.  Nitrogen nqcc's in Piperidine, equatorial (MHz).  Calculation was made on the ropt and reSE molecular structures.
 
 










Calc /ropt
Calc /reSE
Expt. [2]
 
 







14N Xaa
2.152
2.180
2.1007(42)


Xbb
2.738
2.724
2.7557(33)


Xcc - 4.890 -
 4.904
 - 4.8564(39)


|Xac|
0.908
0.865




 








RMS
0.037 (1.1 %)
0.056 (1.7 %)
 


RSD
0.030 (1.3 %)
0.030 (1.3 %)




 








Xxx
2.268
2.283




Xyy
2.738
2.724




Xzz - 5.005 -
 5.008




ETA
0.094
0.088




Øz,a
97.23
96.86




Øa,NH
13.52
13.68




Øz,NH
110.76
110.54




 








 








 








   








Table 2.  Nitrogen and Deuterium nqcc's in N-Deutero-Piperidine, equatorial.  Calculation was made on the on the ropt and reSE molecular structures.
   











Calc /ropt
Calc /reSE
Expt. [2]
   








14N /MHz
 Xaa
2.155
2.182
2.122(6)


Xbb
2.738
2.724
2.743(5)


Xcc - 4.893 -
 4.906
 - 4.865(7)


|Xac|
0.898
0.855



 









RMS
0.025 (0.77 %)
0.043 (1.3 %)
 


RSD
0.030 (1.3 %)
0.030 (1.3 %)



 








 2H /kHz
 Xaa
227.7
225.9
232(9)


Xbb - 101.9 -
 101.1
 - 117(9)

  Xcc - 125.8 -
 124.8
 - 115(15)

  |Xac|
  84.6
  84.4



 









RMS
11.0 (9.5 %)
11.5 (10. %)




RSD
  1.1 (0.86 %)
  1.1 (0.86 %)



 








  Xxx - 145.0 -
 144.2




Xyy - 101.9 -
 101.1




Xzz
246.9
245.3




ETA - 0.174
0.176




Øz,a
12.78
12.91




Øa,ND
13.61
13.76




Øz,ND
  0.83
  0.84



 









 








 








   






Table 3.  Nitrogen nqcc's in Piperidine, axial (MHz).  Calculation was made on the MP2/6-311+G(2d,2p) optimized structure.
   









Calc.
Expt. [2]
   






14N Xaa - 3.740 - 3.6763(11)


Xbb
2.790
2.8013(12)


Xcc
0.951
0.8750(16)


|Xac|
2.900



 







RMS
0.058 (2.4 %)
 


RSD
0.030 (1.3 %)



 







Xxx
2.336




Xyy
2.790



  Xzz - 5.125



  ETA
0.088




Øz,a
25.52




Øa,NH
95.37




Øz,NH
69.85



 







 








 








   






Table 4.  Nitrogen and Deuterium nqcc's in N-Deutero-Piperidine, axial.  Calculation was made on the MP2/6-311+G(2d,2p) optimized structure.
   









Calc.
Expt. [2]
   






14N (MHz) Xaa - 3.617 - 3.578(7)


Xbb
2.790
2.806(5)


Xcc
0.828
0.772(8)


|Xac|
2.996



 







RMS
0.040 (1.7 %)
 


RSD
0.030 (1.3 %)



 






 2H (kHz) Xaa - 137.0 - 147(12)


Xbb - 100.1 - 101(10)

  Xcc
237.1
248(9)

  |Xac|
  50.7



 







RMS
8.5 (5.2 %)




RSD
1.1 (0.86 %)



 






  Xxx - 143.8




Xyy - 100.1




Xzz
243.9




ETA - 0.179




Øz,a
97.58




Øa,ND
96.56




Øz,ND
  1.01



 







 








 








Energy:  Eeq < Eax by 0.93, 0.70, and 0.75 kcal/mol respectively at the MP2/6-311+G(2d,2p), B3PW91/6-311+G(df,pd), and B3LYP/6-31G(df,3p) levels of theory.

 







 
 



Table 5. Selected molecular structure parameters, MP2/6-311+G(2d,2p) ropt and reSE [1] (Å and degrees).  Complete ropt structures are given here in Z-Matirx format.
 





Eq /ropt Eq /reSE Ax /ropt
Equatorial




C(1)N 1.4637 1.4589(2)
 1.4650
NH 1.0107 1.0116(3) 1.0131
C(1)C(2) 1.5232 1.5212(2)
 1.5292
C(2)C(3) 1.5284 1.5255(2)
 1.5283
C(1)H(10) 1.0879 1.0897(5)
 1.0882

C(1)H(11) 1.1004 1.1020(5)
 1.0922

C(2)H(12) 1.0901 1.0918(5)
 1.0925
Axial C(2)H(13) 1.0894 1.0909(5)
 1.0903

C(3)H(8) 1.0926 1.0943(5)
 1.0927
C(3)H(9) 1.0890 1.0906(5)
 1.0889
C(1)NH(7)
 109.73
 109.70(3)
 108.91
C(5)NC(1) 111.17 111.34(2)
 111.43
NC(1)C(2) 109.18 109.37(2)
 113.93
C(1)C(2)C(3) 110.21 110.31(2)
 110.26
C(2)C(3)C(4) 110.46 110.57(2)
 110.26
NC(1)H(10) 108.56 108.63(8)
 107.10
NC(1)H(11) 111.91 111.91(9)
 109.02
C(1)C(2)H(12) 108.54 108.56(12)
 110.10

C(1)C(2)H(13) 109.89 109.87(8)
 109.43

C(2)C3)H(8) 109.03 109.02(4)
 109.00

C(2)C(3)H(9) 110.67 110.62(4)
 110.81



 








 














Table 6.  Piperidine.  Rotational Constants (MHz).  Normal Species.
 





  eq ropt eq Expt. [1] ax ropt  ax Expt. [1]







A 4563.3 4527.2300(28)
 4532.3
 4494.3030(67)

B 4475.6 4437.2288(28)
 4425.9
 4395.2753(67)

C 2566.6 2542.9810(32)
 2556.0
 2535.6089(70)


 








 








[1] J.Demaison, N.C.Craig, P.Groner, P.Écija, E.J.Cocinero, A.Lesarri, and H.D.Rudolph, J.Phys.Chem. A 119(9),1486(2015): Equatorial reSE and, for 14N, 1.5Xaa = 3.1498(71) MHz, 0.25(Xbb - Xcc) = 1.8989(25) MHz.

[2] H.Ehrlichmann, J.-U.Grabow, H.Dreizler, N.Heineking, and M.Andolfatto, Z.Naturforsch. 44a,841(1989).

 








U.Spoerel and W.Stahl, Chem.Phys. 239,97(1998).  In equatorial piperidine: Xaa(14N) = 2.1026(51), Xbb = 2.751, and Xcc = -4.8550 MHz.

J.E.Parkin, P.J.Buckley, and C.C.Costain, J.Mol.Spectrosc. 89,465(1981): For the axial conformer, Xaa = -3.80, Xbb = 2.91, and Xcc = 0.83 MHz; and for the equatorial conformer, Xcc = -4.83 MHz.

 








 








Morpholine Pyridine Pyrrolidine Pyrrole

Dimethylamine





 








 








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Molecules/Nitrogen




Molecules/Deuterium




 













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Last Modified 6 Feb 2015