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 molecular structures given by MP2/6-311+G(2d,2p) optimization.  These are compared with the experimental nqcc's [1] 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 nqcc's.
 
 
   







Table 1.  Nitrogen nqcc's in Piperidine, equatorial (MHz).  Calculation was made on the MP2/6-311+G(2d,2p) optimized structure.
   










Calc.
Expt. [1]
   






14N Xaa 2.152 2.1007(42)
Xbb 2.738 2.7557(33)
Xcc - 4.890 - 4.8564(39)
|Xac| 0.908
 
RMS 0.037 (1.1 %)  
RSD 0.030 (1.3 %)
 
Xxx 2.268
Xyy 2.738
  Xzz - 5.005
  ETA 0.094
Øz,a 82.77
Øa,NH 13.52
Øz,NH 69.24
 
 
 
   







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










Calc.
Expt. [1]
   






14N (MHz) Xaa 2.155 2.122(6)
Xbb 2.738 2.743(5)
Xcc - 4.893 - 4.865(7)
|Xac| 0.898
 
RMS 0.025 (0.77 %)  
RSD 0.030 (1.3 %)
 
 2H (kHz) Xaa 227.7 232(9)
Xbb - 101.9 - 117(9)
  Xcc - 125.8 - 115(15)
  |Xac|   84.6
 
RMS 11.0 (7.1 %)
RSD   1.1 (0.86 %)
 
  Xxx - 145.0
Xyy - 101.9
Xzz 246.9
ETA - 0.174
Øz,a 12.78
Øa,ND 13.61
Øz,ND   0.83
 
 
 
   







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










Calc.
Expt. [1]
   






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. [1]
   






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. Molecular structure parameters, MP2/6-311+G(2d,2p) ropt (Å and degrees).
 
Equatorial Axial
Equatorial

C(1)N 1.4637 1.4650
NH 1.0107 1.0131
C(1)C(2) 1.5232 1.5292
C(2)C(3) 1.5284 1.5283
C(1)H(10) 1.0879 1.0882
C(1)H(11) 1.1004 1.0922
C(2)H(12) 1.0901 1.0925
Axial C(2)H(13) 1.0894 1.0903

C(3)H(8) 1.0926 1.0927
C(3)H(9) 1.0890 1.0889
C(5)NC(1) 111.17 111.43
NC(1)C(2) 109.18 113.93
C(1)C(2)C(3) 110.21 110.26
C(2)C(3)C(4) 110.46 110.26
NC(1)H(10) 108.56 107.10
NC(1)H(11) 111.91 109.02
C(1)C(2)H(12) 108.54 110.10
Dihedral angles? C(1)C(2)H(13) 109.89 109.43
See Z-Matrix. C(2)C3)H(8) 109.03 109.00
C(2)C3)H(9) 110.67 110.81


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

 







 

Morpholine Pyridine Pyrrolidine Pyrrole

Dimethylamine
 

 








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Last Modified 29 Dec 2005